diff --git a/configure.ac b/configure.ac
index dece25a2..19954f1f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -405,6 +405,8 @@ AM_CFLAGS="$AM_CFLAGS -Wimplicit-function-declaration"
 AM_CFLAGS="$AM_CFLAGS -Wundef"
 AM_CFLAGS="$AM_CFLAGS -Wfloat-equal -Wredundant-decls"
 AM_CFLAGS="$AM_CFLAGS -fstack-protector-strong -fno-common"
+# stack arrays sized from peer input are a remote stack-exhaustion vector
+AM_CFLAGS="$AM_CFLAGS -Werror=vla"
 AM_CFLAGS="$AM_CFLAGS -std=gnu99 -ggdb3"
 
 # GCC-specific warnings (not supported by clang) — test each one
diff --git a/meson.build b/meson.build
index 9c29537c..18dfe665 100644
--- a/meson.build
+++ b/meson.build
@@ -58,6 +58,8 @@ cc = meson.get_compiler('c')
 add_project_arguments([
   '-Wno-deprecated-declarations',
   '-Wno-unused-parameter',
+  # stack arrays sized from peer input are a remote stack-exhaustion vector
+  '-Werror=vla',
 ], language: 'c')
 
 analyzer_args = []
diff --git a/src/command/cmd_ac.c b/src/command/cmd_ac.c
index 6b24dc22..e8edc040 100644
--- a/src/command/cmd_ac.c
+++ b/src/command/cmd_ac.c
@@ -1955,7 +1955,10 @@ _cmd_ac_complete_params(ProfWin* window, const char* const input, gboolean previ
     }
 
     size_t len = strlen(input);
-    char parsed[len + 1];
+    auto_char char* parsed = malloc(len + 1);
+    if (!parsed) {
+        return NULL;
+    }
     size_t i = 0;
     while (i < len) {
         if (input[i] == ' ') {
diff --git a/src/command/cmd_funcs.c b/src/command/cmd_funcs.c
index 77b6dd96..167aa6d6 100644
--- a/src/command/cmd_funcs.c
+++ b/src/command/cmd_funcs.c
@@ -9644,6 +9644,13 @@ cmd_url_open(ProfWin* window, const char* const command, gchar** args)
         return TRUE;
     }
 
+    // URLs come from received messages: refuse file:, javascript:, data: etc.
+    if (g_strcmp0(scheme, "http") != 0 && g_strcmp0(scheme, "https") != 0
+        && g_strcmp0(scheme, "aesgcm") != 0) {
+        cons_show_error("URL scheme '%s' is not allowed, only http, https and aesgcm URLs can be opened.", scheme);
+        return TRUE;
+    }
+
     auto_gchar gchar* cmd_template = prefs_get_string(PREF_URL_OPEN_CMD);
     if (cmd_template == NULL) {
         cons_show_error("No default `url open` command found in executables preferences.");
@@ -9689,6 +9696,13 @@ cmd_url_save(ProfWin* window, const char* const command, gchar** args)
         return TRUE;
     }
 
+    // URLs come from received messages: refuse file:, javascript:, data: etc.
+    if (g_strcmp0(scheme, "http") != 0 && g_strcmp0(scheme, "https") != 0
+        && g_strcmp0(scheme, "aesgcm") != 0) {
+        cons_show_error("URL scheme '%s' is not allowed, only http, https and aesgcm URLs can be saved.", scheme);
+        return TRUE;
+    }
+
     auto_gchar gchar* cmd_template = prefs_get_string(PREF_URL_SAVE_CMD);
     if (cmd_template == NULL && (g_strcmp0(scheme, "http") == 0 || g_strcmp0(scheme, "https") == 0)) {
         _url_http_method(window, cmd_template, url, path);
diff --git a/src/common.c b/src/common.c
index 009c6f41..7c06b80e 100644
--- a/src/common.c
+++ b/src/common.c
@@ -455,6 +455,47 @@ str_xml_sanitize(const char* const str)
     return g_string_free(sanitized, FALSE);
 }
 
+static gboolean
+_is_neutralized_char(gunichar c)
+{
+    if (c == 0x09 || c == 0x0A || c == 0x0D) { // tab and newlines are legitimate in a body
+        return FALSE;
+    }
+    if (c < 0x20 || (c >= 0x7F && c <= 0x9F)) { // C0 and C1, incl. ESC: terminal escape sequences
+        return TRUE;
+    }
+    // bidi embeddings, overrides and isolates: they reorder what the user sees.
+    // LRM/RLM (U+200E/U+200F) are kept, legitimate RTL text needs them.
+    return (c >= 0x202A && c <= 0x202E) || (c >= 0x2066 && c <= 0x2069);
+}
+
+/**
+ * Replaces control and bidi-reordering characters in untrusted text with U+FFFD.
+ *
+ * Replaced rather than dropped, so the substitution stays visible to the user.
+ */
+gchar*
+str_neutralize_untrusted(const char* const str)
+{
+    if (str == NULL) {
+        return NULL;
+    }
+
+    auto_gchar gchar* valid = g_utf8_make_valid(str, -1);
+    GString* out = g_string_new_len(NULL, (gssize)strlen(valid));
+
+    for (const char* curr = valid; *curr != '\0'; curr = g_utf8_next_char(curr)) {
+        gunichar c = g_utf8_get_char(curr);
+        if (_is_neutralized_char(c)) {
+            g_string_append_unichar(out, 0xFFFD);
+        } else {
+            g_string_append_unichar(out, c);
+        }
+    }
+
+    return g_string_free(out, FALSE);
+}
+
 char*
 release_get_latest(void)
 {
diff --git a/src/common.h b/src/common.h
index 7abcb9fd..2f80fc4a 100644
--- a/src/common.h
+++ b/src/common.h
@@ -161,6 +161,7 @@ gboolean strtoi_range(const char* str, int* saveptr, int min, int max, char** er
 gsize g_diff_to_gsize(const void* end, const void* start);
 int utf8_display_len(const char* const str);
 gchar* str_xml_sanitize(const char* const str);
+gchar* str_neutralize_untrusted(const char* const str);
 
 gboolean string_matches_one_of(const char* what, const char* is, gboolean is_can_be_null, const char* first, ...) __attribute__((sentinel));
 gboolean valid_tls_policy_option(const char* is);
diff --git a/src/event/server_events.c b/src/event/server_events.c
index 71d7af35..eafb0d56 100644
--- a/src/event/server_events.c
+++ b/src/event/server_events.c
@@ -1303,4 +1303,13 @@ _clean_incoming_message(ProfMessage* message)
 {
     _cut(message, "\u200E");
     _cut(message, "\u200F");
+
+    // runs after decryption, so OTR/PGP/OX plaintext is covered too
+    if (message->plain) {
+        auto_gchar gchar* clean = str_neutralize_untrusted(message->plain);
+        if (g_strcmp0(clean, message->plain) != 0) {
+            free(message->plain);
+            message->plain = strdup(clean); // message_free() frees this with free()
+        }
+    }
 }
diff --git a/src/omemo/crypto.c b/src/omemo/crypto.c
index daca6824..f4948d32 100644
--- a/src/omemo/crypto.c
+++ b/src/omemo/crypto.c
@@ -104,7 +104,7 @@ omemo_hmac_sha256_final_func(void* hmac_context, signal_buffer** output, void* u
 {
     gcry_error_t res;
     size_t mac_len = 32;
-    unsigned char out[mac_len];
+    unsigned char out[32];
 
     res = gcry_mac_read(hmac_context, out, &mac_len);
     if (res != GPG_ERR_NO_ERROR) {
@@ -473,14 +473,19 @@ aes256gcm_create_secure_fragment(unsigned char* key, unsigned char* nonce)
     int key_size = OMEMO_AESGCM_KEY_LENGTH;
     int nonce_size = OMEMO_AESGCM_NONCE_LENGTH;
 
-    char* fragment = gcry_malloc_secure((nonce_size + key_size) * 2 + 1);
+    const size_t fragment_size = (size_t)(nonce_size + key_size) * 2 + 1;
+    char* fragment = gcry_malloc_secure(fragment_size);
+    if (fragment == NULL) {
+        return NULL;
+    }
 
     for (int i = 0; i < nonce_size; i++) {
-        sprintf(&(fragment[i * 2]), "%02x", nonce[i]);
+        g_snprintf(&fragment[i * 2], fragment_size - (size_t)i * 2, "%02x", nonce[i]);
     }
 
     for (int i = 0; i < key_size; i++) {
-        sprintf(&(fragment[(i + nonce_size) * 2]), "%02x", key[i]);
+        const size_t offset = (size_t)(i + nonce_size) * 2;
+        g_snprintf(&fragment[offset], fragment_size - offset, "%02x", key[i]);
     }
 
     return fragment;
diff --git a/src/omemo/omemo.c b/src/omemo/omemo.c
index 38157336..0969bbad 100644
--- a/src/omemo/omemo.c
+++ b/src/omemo/omemo.c
@@ -452,8 +452,12 @@ omemo_identity_key(unsigned char** output, size_t* length)
     signal_buffer* buffer = NULL;
     ec_public_key_serialize(&buffer, ratchet_identity_key_pair_get_public(omemo_ctx.identity_key_pair));
     *length = signal_buffer_len(buffer);
-    *output = malloc(*length);
-    memcpy(*output, signal_buffer_data(buffer), *length);
+    // g_malloc aborts instead of returning NULL, but it returns NULL for a zero
+    // length, which memcpy must not be handed
+    *output = *length ? g_malloc(*length) : NULL;
+    if (*output) {
+        memcpy(*output, signal_buffer_data(buffer), *length);
+    }
     signal_buffer_free(buffer);
 }
 
@@ -472,8 +476,10 @@ omemo_signed_prekey(unsigned char** output, size_t* length)
     ec_public_key_serialize(&buffer, ec_key_pair_get_public(session_signed_pre_key_get_key_pair(signed_pre_key)));
     SIGNAL_UNREF(signed_pre_key);
     *length = signal_buffer_len(buffer);
-    *output = malloc(*length);
-    memcpy(*output, signal_buffer_data(buffer), *length);
+    *output = *length ? g_malloc(*length) : NULL;
+    if (*output) {
+        memcpy(*output, signal_buffer_data(buffer), *length);
+    }
     signal_buffer_free(buffer);
 }
 
@@ -489,8 +495,10 @@ omemo_signed_prekey_signature(unsigned char** output, size_t* length)
     }
 
     *length = session_signed_pre_key_get_signature_len(signed_pre_key);
-    *output = malloc(*length);
-    memcpy(*output, session_signed_pre_key_get_signature(signed_pre_key), *length);
+    *output = *length ? g_malloc(*length) : NULL;
+    if (*output) {
+        memcpy(*output, session_signed_pre_key_get_signature(signed_pre_key), *length);
+    }
     SIGNAL_UNREF(signed_pre_key);
 }
 
diff --git a/src/pgp/ox.c b/src/pgp/ox.c
index 65f7894e..4302ae63 100644
--- a/src/pgp/ox.c
+++ b/src/pgp/ox.c
@@ -147,13 +147,8 @@ p_ox_gpg_signcrypt(const char* const sender_barejid, const char* const recipient
     gpgme_set_offline(ctx, 1);
     gpgme_set_keylist_mode(ctx, GPGME_KEYLIST_MODE_LOCAL);
 
-    char* xmpp_jid_me = alloca((strlen(sender_barejid) + 6) * sizeof(char));
-    char* xmpp_jid_recipient = alloca((strlen(recipient_barejid) + 6) * sizeof(char));
-
-    strcpy(xmpp_jid_me, "xmpp:");
-    strcpy(xmpp_jid_recipient, "xmpp:");
-    strcat(xmpp_jid_me, sender_barejid);
-    strcat(xmpp_jid_recipient, recipient_barejid);
+    auto_gchar gchar* xmpp_jid_me = g_strdup_printf("xmpp:%s", sender_barejid);
+    auto_gchar gchar* xmpp_jid_recipient = g_strdup_printf("xmpp:%s", recipient_barejid);
 
     gpgme_signers_clear(ctx);
 
diff --git a/src/plugins/python_api.c b/src/plugins/python_api.c
index 494fff96..9e8522f2 100644
--- a/src/plugins/python_api.c
+++ b/src/plugins/python_api.c
@@ -122,7 +122,7 @@ python_api_register_command(PyObject* self, PyObject* args)
 
     if (p_callback && PyCallable_Check(p_callback)) {
         Py_ssize_t len = PyList_Size(synopsis);
-        char* c_synopsis[len == 0 ? 0 : len + 1];
+        char** c_synopsis = g_malloc_n((size_t)len + 1, sizeof(*c_synopsis));
         Py_ssize_t i = 0;
         for (i = 0; i < len; i++) {
             PyObject* item = PyList_GetItem(synopsis, i);
@@ -132,11 +132,23 @@ python_api_register_command(PyObject* self, PyObject* args)
         c_synopsis[len] = NULL;
 
         Py_ssize_t args_len = PyList_Size(arguments);
-        char* c_arguments[args_len + 1][2];
+        char*(*c_arguments)[2] = g_malloc_n((size_t)args_len + 1, sizeof(*c_arguments));
         for (i = 0; i < args_len; i++) {
             PyObject* item = PyList_GetItem(arguments, i);
             Py_ssize_t len2 = PyList_Size(item);
             if (len2 != 2) {
+                for (Py_ssize_t j = 0; j < len; j++) {
+                    free(c_synopsis[j]);
+                }
+                for (Py_ssize_t j = 0; j < i; j++) {
+                    free(c_arguments[j][0]);
+                    free(c_arguments[j][1]);
+                }
+                g_free(c_synopsis);
+                g_free(c_arguments);
+                free(command_name_str);
+                free(description_str);
+                free(plugin_name);
                 Py_RETURN_NONE;
             }
             PyObject* arg = PyList_GetItem(item, 0);
@@ -152,7 +164,7 @@ python_api_register_command(PyObject* self, PyObject* args)
         c_arguments[args_len][1] = NULL;
 
         len = PyList_Size(examples);
-        char* c_examples[len == 0 ? 0 : len + 1];
+        char** c_examples = g_malloc_n((size_t)len + 1, sizeof(*c_examples));
         for (i = 0; i < len; i++) {
             PyObject* item = PyList_GetItem(examples, i);
             char* c_item = python_str_or_unicode_to_string(item);
@@ -179,6 +191,9 @@ python_api_register_command(PyObject* self, PyObject* args)
         while (c_examples[i] != NULL) {
             free(c_examples[i++]);
         }
+        g_free(c_synopsis);
+        g_free(c_arguments);
+        g_free(c_examples);
         disable_python_threads();
     }
 
@@ -227,7 +242,7 @@ python_api_completer_add(PyObject* self, PyObject* args)
     log_debug("Autocomplete add %s for %s", key_str, plugin_name);
 
     Py_ssize_t len = PyList_Size(items);
-    char* c_items[len];
+    char** c_items = g_malloc_n((size_t)len + 1, sizeof(*c_items)); // + 1 for the NULL terminator below
 
     Py_ssize_t i = 0;
     for (i = 0; i < len; i++) {
@@ -244,6 +259,7 @@ python_api_completer_add(PyObject* self, PyObject* args)
     while (c_items[i] != NULL) {
         free(c_items[i++]);
     }
+    g_free(c_items);
     disable_python_threads();
 
     free(plugin_name);
@@ -267,7 +283,7 @@ python_api_completer_remove(PyObject* self, PyObject* args)
     log_debug("Autocomplete remove %s for %s", key_str, plugin_name);
 
     Py_ssize_t len = PyList_Size(items);
-    char* c_items[len];
+    char** c_items = g_malloc_n((size_t)len + 1, sizeof(*c_items)); // + 1 for the NULL terminator below
 
     Py_ssize_t i = 0;
     for (i = 0; i < len; i++) {
@@ -280,6 +296,11 @@ python_api_completer_remove(PyObject* self, PyObject* args)
     allow_python_threads();
     api_completer_remove(plugin_name, key_str, c_items);
     free(key_str);
+    i = 0;
+    while (c_items[i] != NULL) {
+        free(c_items[i++]);
+    }
+    g_free(c_items);
     disable_python_threads();
 
     free(plugin_name);
diff --git a/src/ui/inputwin.c b/src/ui/inputwin.c
index 1e371f5f..d986a26e 100644
--- a/src/ui/inputwin.c
+++ b/src/ui/inputwin.c
@@ -493,7 +493,7 @@ _inp_edited(const wint_t ch)
     }
 
     // printable
-    char bytes[MB_CUR_MAX + 1];
+    char bytes[PROF_MB_CUR_MAX + 1]; // compile-time bound, the locale value is checked at startup
     size_t utf_len = wcrtomb(bytes, ch, &mbstate);
     if (utf_len == (size_t)-1) {
         return 0;
diff --git a/src/ui/mucwin.c b/src/ui/mucwin.c
index b7944609..cd67f507 100644
--- a/src/ui/mucwin.c
+++ b/src/ui/mucwin.c
@@ -454,22 +454,10 @@ _mucwin_print_triggers(ProfWin* window, const char* const message, GList* trigge
         win_appendln_highlight(window, THEME_ROOMTRIGGER, "%s", message);
     } else {
         if (first_trigger_pos > 0) {
-            char message_section[strlen(message) + 1];
-            int i = 0;
-            while (i < first_trigger_pos) {
-                message_section[i] = message[i];
-                i++;
-            }
-            message_section[i] = '\0';
+            auto_gchar gchar* message_section = g_strndup(message, (gsize)first_trigger_pos);
             win_append_highlight(window, THEME_ROOMTRIGGER, "%s", message_section);
         }
-        char trigger_section[first_trigger_len + 1];
-        int i = 0;
-        while (i < first_trigger_len) {
-            trigger_section[i] = message[first_trigger_pos + i];
-            i++;
-        }
-        trigger_section[i] = '\0';
+        auto_gchar gchar* trigger_section = g_strndup(&message[first_trigger_pos], (gsize)first_trigger_len);
 
         if (first_trigger_pos + first_trigger_len < (int)strlen(message)) {
             win_append_highlight(window, THEME_ROOMTRIGGER_TERM, "%s", trigger_section);
diff --git a/src/ui/notifier.c b/src/ui/notifier.c
index 9b4c676f..244e6bcc 100644
--- a/src/ui/notifier.c
+++ b/src/ui/notifier.c
@@ -22,6 +22,7 @@
 #include <windows.h>
 #endif
 
+#include "common.h"
 #include "log.h"
 #include "config/preferences.h"
 #include "ui/ui.h"
@@ -122,47 +123,42 @@ _notify(const char* const message, int timeout, const char* const category)
 static void
 _notify(const char* const message, int timeout, const char* const category)
 {
-    GString* notify_command = g_string_new("terminal-notifier -title \"Profanity\" -message '");
+    if (message == NULL) {
+        return;
+    }
 
-    auto_char char* escaped_single = str_replace(message, "'", "'\\''");
-
-    if (escaped_single[0] == '<') {
-        g_string_append(notify_command, "\\<");
-        g_string_append(notify_command, &escaped_single[1]);
-    } else if (escaped_single[0] == '[') {
-        g_string_append(notify_command, "\\[");
-        g_string_append(notify_command, &escaped_single[1]);
-    } else if (escaped_single[0] == '(') {
-        g_string_append(notify_command, "\\(");
-        g_string_append(notify_command, &escaped_single[1]);
-    } else if (escaped_single[0] == '{') {
-        g_string_append(notify_command, "\\{");
-        g_string_append(notify_command, &escaped_single[1]);
+    // terminal-notifier swallows a leading <, [, ( or { — escape it for its parser
+    auto_gchar gchar* msg = NULL;
+    if (message[0] == '<' || message[0] == '[' || message[0] == '(' || message[0] == '{') {
+        msg = g_strdup_printf("\\%s", message);
     } else {
-        g_string_append(notify_command, escaped_single);
+        msg = g_strdup(message);
     }
 
-    g_string_append(notify_command, "'");
+    const gchar* argv[16]; // headroom: an added flag must not silently overrun
+    guint i = 0;
+    argv[i++] = "terminal-notifier";
+    argv[i++] = "-title";
+    argv[i++] = "Profanity";
+    argv[i++] = "-message";
+    argv[i++] = msg;
 
-    char* term_name = getenv("TERM_PROGRAM");
-    char* app_id = NULL;
+    const char* term_name = getenv("TERM_PROGRAM");
     if (g_strcmp0(term_name, "Apple_Terminal") == 0) {
-        app_id = "com.apple.Terminal";
+        argv[i++] = "-sender";
+        argv[i++] = "com.apple.Terminal";
     } else if (g_strcmp0(term_name, "iTerm.app") == 0) {
-        app_id = "com.googlecode.iterm2";
+        argv[i++] = "-sender";
+        argv[i++] = "com.googlecode.iterm2";
     }
+    argv[i] = NULL;
 
-    if (app_id) {
-        g_string_append(notify_command, " -sender ");
-        g_string_append(notify_command, app_id);
+    GError* err = NULL;
+    // argv-based spawn: the message is one argument, the shell never sees it
+    if (!g_spawn_async(NULL, (gchar**)argv, NULL, G_SPAWN_SEARCH_PATH, NULL, NULL, NULL, &err)) {
+        log_error("Could not send desktop notification: %s", err->message);
+        g_error_free(err);
     }
-
-    int res = system(notify_command->str);
-    if (res == -1) {
-        log_error("Could not send desktop notification.");
-    }
-
-    g_string_free(notify_command, TRUE);
 }
 #else
 static void
diff --git a/src/ui/window.c b/src/ui/window.c
index 4cbbbb71..daf6d770 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -32,6 +32,7 @@
 #include <curses.h>
 #endif
 
+#include "common.h"
 #include "log.h"
 #include "config/theme.h"
 #include "config/preferences.h"
@@ -2115,7 +2116,7 @@ _win_print_wrapped(WINDOW* win, const char* const message, int indent, int pad_i
                             _win_indent(win, indent + pad_indent);
                         }
 
-                        gchar copy[wordi + 1];
+                        gchar copy[PROF_MB_CUR_MAX + 1]; // one UTF-8 character, not the whole word
                         g_utf8_strncpy(copy, word_ch, 1);
                         waddstr(win, copy);
 
diff --git a/src/xmpp/capabilities.c b/src/xmpp/capabilities.c
index 3e788d80..303c09c8 100644
--- a/src/xmpp/capabilities.c
+++ b/src/xmpp/capabilities.c
@@ -247,14 +247,16 @@ caps_add_by_ver(const char* const ver, EntityCapabilities* caps)
 
     if (caps->features) {
         GSList* curr_feature = caps->features;
-        int num = g_slist_length(caps->features);
-        const gchar* features_list[num];
-        int curr = 0;
+        // the feature count comes from a disco#info response, keep it off the stack
+        guint num = g_slist_length(caps->features);
+        const gchar** features_list = g_malloc_n(num, sizeof(*features_list));
+        guint curr = 0;
         while (curr_feature) {
             features_list[curr++] = curr_feature->data;
             curr_feature = g_slist_next(curr_feature);
         }
         g_key_file_set_string_list(cache, ver, "features", features_list, num);
+        g_free(features_list);
     }
 
     _save_cache();
diff --git a/src/xmpp/iq.c b/src/xmpp/iq.c
index 1c9869f5..f1757a24 100644
--- a/src/xmpp/iq.c
+++ b/src/xmpp/iq.c
@@ -1784,7 +1784,7 @@ _last_activity_get_handler(xmpp_stanza_t* const stanza)
     if (prefs_get_boolean(PREF_LASTACTIVITY)) {
         int idls_secs = (int)(ui_get_idle_time() / 1000);
         char str[50];
-        sprintf(str, "%d", idls_secs);
+        g_snprintf(str, sizeof(str), "%d", idls_secs);
 
         xmpp_stanza_t* response = xmpp_iq_new(ctx, STANZA_TYPE_RESULT, xmpp_stanza_get_id(stanza));
         xmpp_stanza_set_to(response, from);
diff --git a/src/xmpp/message.c b/src/xmpp/message.c
index 2de5ea4e..08553d2e 100644
--- a/src/xmpp/message.c
+++ b/src/xmpp/message.c
@@ -1562,6 +1562,20 @@ _handle_mam(xmpp_stanza_t* const stanza)
 
     const char* result_id = xmpp_stanza_get_id(result);
 
+    // XEP-0359 §6 gate, same as for live <stanza-id>: only keep the archive
+    // id if the archive's owner announces stable ids
+    if (result_id) {
+        const char* archive = by ? by : from;
+        if (archive == NULL) {
+            const Jid* myjid = connection_get_jid();
+            archive = myjid ? myjid->barejid : NULL;
+        }
+        if (!_stanza_id_by_trusted(archive)) {
+            log_debug("MAM result id dropped: archive %s does not announce XEP-0359 support", STR_MAYBE_NULL(archive));
+            result_id = NULL;
+        }
+    }
+
     GDateTime* timestamp = stanza_get_delay_from(forwarded, NULL);
 
     xmpp_stanza_t* message_stanza = xmpp_stanza_get_child_by_ns(forwarded, "jabber:client");
@@ -1658,7 +1672,7 @@ _ox_openpgp_signcrypt(xmpp_ctx_t* ctx, const char* const to, const char* const t
 
     // build rpad
     int randnr = (rand() % 100) + 1;
-    char rpad_data[randnr];
+    char rpad_data[101];
     for (int i = 0; i < randnr; i++) {
         int rchar = (rand() % 52) + 65;
         rpad_data[i] = (char)rchar;
@@ -1747,6 +1761,10 @@ _should_ignore_based_on_silence(xmpp_stanza_t* const stanza)
     if (prefs_get_boolean(PREF_SILENCE_NON_ROSTER)) {
         const char* const from = xmpp_stanza_get_from(stanza);
         auto_jid Jid* from_jid = jid_create(from);
+        if (from_jid == NULL) { // no usable sender: treat as non-roster and ignore
+            log_debug("[Silence] Ignoring message with missing or invalid from attribute");
+            return TRUE;
+        }
         PContact contact = roster_get_contact(from_jid->barejid);
         if (!contact) {
             log_debug("[Silence] Ignoring message from: %s", from);
diff --git a/src/xmpp/omemo.c b/src/xmpp/omemo.c
index 840deba5..31194f39 100644
--- a/src/xmpp/omemo.c
+++ b/src/xmpp/omemo.c
@@ -130,9 +130,9 @@ omemo_bundle_publish(gboolean first)
     iq_send_stanza(iq);
 
     xmpp_stanza_release(iq);
-    free(identity_key);
-    free(signed_prekey);
-    free(signed_prekey_signature);
+    g_free(identity_key);
+    g_free(signed_prekey);
+    g_free(signed_prekey_signature);
     free(id);
 }
 
diff --git a/src/xmpp/presence.c b/src/xmpp/presence.c
index 8ab4625d..9f5378bc 100644
--- a/src/xmpp/presence.c
+++ b/src/xmpp/presence.c
@@ -395,6 +395,10 @@ _presence_error_handler(xmpp_stanza_t* const stanza)
         }
 
         auto_jid Jid* fulljid = jid_create(from);
+        if (fulljid == NULL) {
+            log_warning("MUC error presence received with missing or invalid from attribute");
+            return;
+        }
         log_info("Error joining room: %s, reason: %s", fulljid->barejid, error_cond);
         if (muc_active(fulljid->barejid)) {
             muc_leave(fulljid->barejid);
@@ -451,6 +455,9 @@ _unsubscribed_handler(xmpp_stanza_t* const stanza)
     log_debug("Unsubscribed presence handler fired for %s", from);
 
     auto_jid Jid* from_jid = jid_create(from);
+    if (from_jid == NULL) {
+        return;
+    }
     sv_ev_subscription(from_jid->barejid, PRESENCE_UNSUBSCRIBED);
     autocomplete_remove(sub_requests_ac, from_jid->barejid);
 }
@@ -466,6 +473,9 @@ _subscribed_handler(xmpp_stanza_t* const stanza)
     log_debug("Subscribed presence handler fired for %s", from);
 
     auto_jid Jid* from_jid = jid_create(from);
+    if (from_jid == NULL) {
+        return;
+    }
     sv_ev_subscription(from_jid->barejid, PRESENCE_SUBSCRIBED);
     autocomplete_remove(sub_requests_ac, from_jid->barejid);
 }
@@ -476,6 +486,7 @@ _subscribe_handler(xmpp_stanza_t* const stanza)
     const char* from = xmpp_stanza_get_from(stanza);
     if (!from) {
         log_warning("Subscribe presence handler received with no from attribute");
+        return;
     }
     log_debug("Subscribe presence handler fired for %s", from);
 
@@ -728,6 +739,9 @@ _muc_user_self_handler(xmpp_stanza_t* stanza)
 {
     const char* from = xmpp_stanza_get_from(stanza);
     auto_jid Jid* from_jid = jid_create(from);
+    if (from_jid == NULL) { // caller validates, but don't rely on it
+        return;
+    }
 
     log_debug("Room self presence received from %s", from_jid->fulljid);
 
@@ -810,6 +824,9 @@ _muc_user_occupant_handler(xmpp_stanza_t* stanza)
 {
     const char* from = xmpp_stanza_get_from(stanza);
     auto_jid Jid* from_jid = jid_create(from);
+    if (from_jid == NULL) { // caller validates, but don't rely on it
+        return;
+    }
 
     log_debug("Room presence received from %s", from_jid->fulljid);
 
diff --git a/tests/functionaltests/functionaltests.c b/tests/functionaltests/functionaltests.c
index da68145e..d7629868 100644
--- a/tests/functionaltests/functionaltests.c
+++ b/tests/functionaltests/functionaltests.c
@@ -238,6 +238,8 @@ main(int argc, char* argv[])
         PROF_FUNC_TEST(presence_keeps_status),
         PROF_FUNC_TEST(presence_received),
         PROF_FUNC_TEST(presence_missing_resource_defaults),
+        PROF_FUNC_TEST(presence_error_invalid_from_no_crash),
+        PROF_FUNC_TEST(presence_subscription_invalid_from_no_crash),
 
         /* Disconnect - clean session termination */
         PROF_FUNC_TEST(disconnect_ends_session),
@@ -261,6 +263,7 @@ main(int argc, char* argv[])
         PROF_FUNC_TEST(message_send),
         PROF_FUNC_TEST(message_receive_console),
         PROF_FUNC_TEST(message_receive_chatwin),
+        PROF_FUNC_TEST(message_invalid_from_silence_no_crash),
 
         /* XEP-0359 disco gate for stanza-id trust */
         PROF_FUNC_TEST(stanza_id_dedup_fires_when_server_announces_sid0),
diff --git a/tests/functionaltests/test_message.c b/tests/functionaltests/test_message.c
index 402144ac..e27a3177 100644
--- a/tests/functionaltests/test_message.c
+++ b/tests/functionaltests/test_message.c
@@ -123,3 +123,29 @@ stanza_id_not_trusted_when_server_does_not_announce_sid0(void **state)
     assert_false(prof_output_exact("Got a message with duplicate (server-generated) stanza-id"));
     prof_timeout_reset();
 }
+
+/* Regression test for issue #148 (REQ-INP-01): with silence.non-roster
+ * enabled the incoming-message filter dereferenced jid_create() without a
+ * NULL check, so a message with an invalid 'from' crashed the client. */
+void
+message_invalid_from_silence_no_crash(void **state)
+{
+    prof_connect();
+
+    prof_input("/silence on");
+    assert_true(prof_output_exact("Block all messages from JIDs that are not in the roster enabled."));
+
+    stbbr_send(
+        "<message to='stabber@localhost' from='bad@@jid' type='chat'>"
+            "<body>should be dropped, not crash</body>"
+        "</message>"
+    );
+
+    /* client is still alive: a roster contact's message comes through */
+    stbbr_send(
+        "<message to='stabber@localhost' from='buddy1@localhost/mobile' type='chat'>"
+            "<body>still alive</body>"
+        "</message>"
+    );
+    assert_true(prof_output_exact("<< chat message: Buddy1/mobile (win 2)"));
+}
diff --git a/tests/functionaltests/test_message.h b/tests/functionaltests/test_message.h
index 924ad914..1d179918 100644
--- a/tests/functionaltests/test_message.h
+++ b/tests/functionaltests/test_message.h
@@ -3,3 +3,4 @@ void message_receive_console(void **state);
 void message_receive_chatwin(void **state);
 void stanza_id_dedup_fires_when_server_announces_sid0(void **state);
 void stanza_id_not_trusted_when_server_does_not_announce_sid0(void **state);
+void message_invalid_from_silence_no_crash(void **state);
diff --git a/tests/functionaltests/test_presence.c b/tests/functionaltests/test_presence.c
index 8cb05a36..6e417e6b 100644
--- a/tests/functionaltests/test_presence.c
+++ b/tests/functionaltests/test_presence.c
@@ -289,3 +289,53 @@ presence_missing_resource_defaults(void **state)
 
     assert_true(prof_output_exact("__prof_default (15), online"));
 }
+
+/* Regression tests for issue #148 (REQ-INP-01): presence handlers used to
+ * dereference jid_create() results without a NULL check, so a stanza with a
+ * missing or invalid 'from' crashed the client. */
+void
+presence_error_invalid_from_no_crash(void **state)
+{
+    prof_connect();
+
+    /* MUC join error with an invalid 'from' */
+    stbbr_send(
+        "<presence to='stabber@localhost' from='bad@@room' type='error'>"
+            "<x xmlns='http://jabber.org/protocol/muc'/>"
+            "<error type='cancel'><not-allowed xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/></error>"
+        "</presence>"
+    );
+
+    /* same, with no 'from' at all */
+    stbbr_send(
+        "<presence to='stabber@localhost' type='error'>"
+            "<x xmlns='http://jabber.org/protocol/muc'/>"
+            "<error type='cancel'><not-allowed xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/></error>"
+        "</presence>"
+    );
+
+    /* client is still alive and processing stanzas */
+    stbbr_send(
+        "<presence to='stabber@localhost' from='buddy1@localhost/mobile'>"
+            "<status>still alive</status>"
+        "</presence>"
+    );
+    assert_true(prof_output_exact("Buddy1 (mobile) is online, \"still alive\""));
+}
+
+void
+presence_subscription_invalid_from_no_crash(void **state)
+{
+    prof_connect();
+
+    stbbr_send("<presence to='stabber@localhost' from='bad@@jid' type='subscribed'/>");
+    stbbr_send("<presence to='stabber@localhost' from='bad@@jid' type='unsubscribed'/>");
+    stbbr_send("<presence to='stabber@localhost' from='bad@@jid' type='subscribe'/>");
+
+    stbbr_send(
+        "<presence to='stabber@localhost' from='buddy1@localhost/mobile'>"
+            "<status>still alive</status>"
+        "</presence>"
+    );
+    assert_true(prof_output_exact("Buddy1 (mobile) is online, \"still alive\""));
+}
diff --git a/tests/functionaltests/test_presence.h b/tests/functionaltests/test_presence.h
index 107fa794..3648bd27 100644
--- a/tests/functionaltests/test_presence.h
+++ b/tests/functionaltests/test_presence.h
@@ -13,3 +13,5 @@ void presence_includes_priority(void **state);
 void presence_keeps_status(void **state);
 void presence_received(void **state);
 void presence_missing_resource_defaults(void **state);
+void presence_error_invalid_from_no_crash(void **state);
+void presence_subscription_invalid_from_no_crash(void **state);
diff --git a/tests/unittests/test_common.c b/tests/unittests/test_common.c
index 7e876ecf..578dc5ff 100644
--- a/tests/unittests/test_common.c
+++ b/tests/unittests/test_common.c
@@ -1384,3 +1384,43 @@ str_xml_sanitize__strips_illegal_characters(void** state)
     assert_string_equal("UTF-8: üñîçøðé  and more", res5);
     g_free(res5);
 }
+
+void
+neutralize_untrusted_keeps_plain_text(void** state)
+{
+    gchar* result = str_neutralize_untrusted("hello world\ttabbed\nnewline");
+    assert_string_equal("hello world\ttabbed\nnewline", result);
+    g_free(result);
+}
+
+void
+neutralize_untrusted_replaces_escape_sequence(void** state)
+{
+    gchar* result = str_neutralize_untrusted("safe\x1b[31mred");
+    assert_string_equal("safe\xef\xbf\xbd[31mred", result);
+    g_free(result);
+}
+
+void
+neutralize_untrusted_replaces_bidi_override(void** state)
+{
+    // U+202E RIGHT-TO-LEFT OVERRIDE
+    gchar* result = str_neutralize_untrusted("file\xe2\x80\xaegnp.exe");
+    assert_string_equal("file\xef\xbf\xbdgnp.exe", result);
+    g_free(result);
+}
+
+void
+neutralize_untrusted_keeps_rtl_marks(void** state)
+{
+    // U+200F RIGHT-TO-LEFT MARK is legitimate in RTL text
+    gchar* result = str_neutralize_untrusted("\xe2\x80\x8fשלום");
+    assert_string_equal("\xe2\x80\x8fשלום", result);
+    g_free(result);
+}
+
+void
+neutralize_untrusted_handles_null(void** state)
+{
+    assert_null(str_neutralize_untrusted(NULL));
+}
diff --git a/tests/unittests/test_common.h b/tests/unittests/test_common.h
index 277a7cdb..8ad5eac1 100644
--- a/tests/unittests/test_common.h
+++ b/tests/unittests/test_common.h
@@ -66,3 +66,8 @@ void release_is_new__tests__various(void** state);
 void str_xml_sanitize__strips_illegal_characters(void** state);
 
 #endif
+void neutralize_untrusted_keeps_plain_text(void** state);
+void neutralize_untrusted_replaces_escape_sequence(void** state);
+void neutralize_untrusted_replaces_bidi_override(void** state);
+void neutralize_untrusted_keeps_rtl_marks(void** state);
+void neutralize_untrusted_handles_null(void** state);
diff --git a/tests/unittests/unittests.c b/tests/unittests/unittests.c
index cf01788e..0598a862 100644
--- a/tests/unittests/unittests.c
+++ b/tests/unittests/unittests.c
@@ -183,6 +183,11 @@ main(int argc, char* argv[])
         cmocka_unit_test(jid_is_valid_user_jid__is__true_for_at_in_resource),
         cmocka_unit_test(jid_is_valid_user_jid__is__false_for_domain_jid),
         cmocka_unit_test(jid_is_valid_user_jid__is__false_for_invalid_jid),
+        cmocka_unit_test(jid_is_valid__boundary__localpart_length),
+        cmocka_unit_test(jid_is_valid__boundary__domainpart_length),
+        cmocka_unit_test(jid_is_valid__boundary__resourcepart_length),
+        cmocka_unit_test(jid_is_valid__boundary__total_length),
+        cmocka_unit_test(jid_is_valid__is__false_for_invalid_utf8),
         cmocka_unit_test(jid_is_valid__is__true_for_valid_jid),
         cmocka_unit_test(jid_is_valid__is__false_for_invalid_jid),
         cmocka_unit_test(jid_is_valid__is__false_for_null),
@@ -687,6 +692,11 @@ main(int argc, char* argv[])
         cmocka_unit_test(get_mentions__tests__various),
         cmocka_unit_test(release_is_new__tests__various),
         cmocka_unit_test(str_xml_sanitize__strips_illegal_characters),
+        cmocka_unit_test(neutralize_untrusted_keeps_plain_text),
+        cmocka_unit_test(neutralize_untrusted_replaces_escape_sequence),
+        cmocka_unit_test(neutralize_untrusted_replaces_bidi_override),
+        cmocka_unit_test(neutralize_untrusted_keeps_rtl_marks),
+        cmocka_unit_test(neutralize_untrusted_handles_null),
 
         cmocka_unit_test_setup_teardown(plugins_get_command_names__returns__no_commands,
                                         load_preferences,
diff --git a/tests/unittests/xmpp/test_jid.c b/tests/unittests/xmpp/test_jid.c
index e2b2ede0..0c731f29 100644
--- a/tests/unittests/xmpp/test_jid.c
+++ b/tests/unittests/xmpp/test_jid.c
@@ -370,3 +370,75 @@ jid_is_valid__is__false_for_empty_string(void** state)
 {
     assert_false(jid_is_valid(""));
 }
+
+/* RFC 6122 size limits: 1023 bytes per part, 3071 for the full JID */
+void
+jid_is_valid__boundary__localpart_length(void** state)
+{
+    gchar* local_ok = g_strnfill(1023, 'a');
+    gchar* jid_ok = g_strdup_printf("%s@domain", local_ok);
+    assert_true(jid_is_valid(jid_ok));
+
+    gchar* local_over = g_strnfill(1024, 'a');
+    gchar* jid_over = g_strdup_printf("%s@domain", local_over);
+    assert_false(jid_is_valid(jid_over));
+
+    g_free(local_ok);
+    g_free(jid_ok);
+    g_free(local_over);
+    g_free(jid_over);
+}
+
+void
+jid_is_valid__boundary__domainpart_length(void** state)
+{
+    gchar* domain_ok = g_strnfill(1023, 'd');
+    assert_true(jid_is_valid(domain_ok));
+
+    gchar* domain_over = g_strnfill(1024, 'd');
+    assert_false(jid_is_valid(domain_over));
+
+    g_free(domain_ok);
+    g_free(domain_over);
+}
+
+void
+jid_is_valid__boundary__resourcepart_length(void** state)
+{
+    gchar* res_ok = g_strnfill(1023, 'r');
+    gchar* jid_ok = g_strdup_printf("user@domain/%s", res_ok);
+    assert_true(jid_is_valid(jid_ok));
+
+    gchar* res_over = g_strnfill(1024, 'r');
+    gchar* jid_over = g_strdup_printf("user@domain/%s", res_over);
+    assert_false(jid_is_valid(jid_over));
+
+    g_free(res_ok);
+    g_free(jid_ok);
+    g_free(res_over);
+    g_free(jid_over);
+}
+
+void
+jid_is_valid__boundary__total_length(void** state)
+{
+    // 1023 + '@' + 1023 + '/' + 1023 = 3071, the largest legal JID
+    gchar* local = g_strnfill(1023, 'a');
+    gchar* domain = g_strnfill(1023, 'd');
+    gchar* res = g_strnfill(1023, 'r');
+    gchar* jid_max = g_strdup_printf("%s@%s/%s", local, domain, res);
+    assert_true(jid_is_valid(jid_max));
+
+    g_free(local);
+    g_free(domain);
+    g_free(res);
+    g_free(jid_max);
+}
+
+void
+jid_is_valid__is__false_for_invalid_utf8(void** state)
+{
+    assert_false(jid_is_valid("user\xff\xfe@domain"));
+    assert_false(jid_is_valid("us\xc3@domain")); // truncated multi-byte sequence
+    assert_false(jid_is_valid("user@domain/res\x80")); // stray continuation byte
+}
diff --git a/tests/unittests/xmpp/test_jid.h b/tests/unittests/xmpp/test_jid.h
index 7543f903..b8aaa9e4 100644
--- a/tests/unittests/xmpp/test_jid.h
+++ b/tests/unittests/xmpp/test_jid.h
@@ -41,3 +41,8 @@ void jid_is_valid__is__false_for_null(void** state);
 void jid_is_valid__is__false_for_empty_string(void** state);
 
 #endif
+void jid_is_valid__boundary__localpart_length(void** state);
+void jid_is_valid__boundary__domainpart_length(void** state);
+void jid_is_valid__boundary__resourcepart_length(void** state);
+void jid_is_valid__boundary__total_length(void** state);
+void jid_is_valid__is__false_for_invalid_utf8(void** state);