new file mode 100644
@@ -0,0 +1,140 @@
+From 6ced6ddb7c85bd7b6bd614835c030983078662d6 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@gnome.org>
+Date: Tue, 28 Apr 2026 16:45:14 +0100
+Subject: [PATCH] giochannel: Fix memcmp() off the end of the buffer with long
+ terminators
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If the line terminator is longer than a single byte, and the current
+line extends to the end of the buffer, and the buffer (which is a
+`GString`) is near a power of two in length (as that’s how `GString`s
+are allocated) it’s possible for the `memcmp()` which checks the
+terminator to read off the end of the string buffer.
+
+Fix that by checking the terminator length against the last character
+before calling `memcmp()`. Add a unit test.
+
+Spotted by linhlhq as #YWH-PGM9867-199. The fix is theirs (validated by
+me), and the unit test is adapted from their proof of concept.
+
+Fixes: #3925
+
+CVE: CVE-2026-58013
+Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/glib/-/commit/6a2583dec39bfe05553b16d9b7419d6c2a257244]
+
+Backport Changes:
+- Added the <stdint.h> include for the regression test because these target
+ branches do not otherwise expose uint8_t in glib/tests/io-channel.c.
+
+Signed-off-by: Philip Withnall <pwithnall@gnome.org>
+(cherry picked from commit 6a2583dec39bfe05553b16d9b7419d6c2a257244)
+Signed-off-by: Deepak Rathore <deeratho@cisco.com>
+---
+ glib/giochannel.c | 3 ++-
+ glib/tests/io-channel.c | 61 +++++++++++++++++++++++++++++++++++++++++
+ 2 files changed, 63 insertions(+), 1 deletion(-)
+
+diff --git a/glib/giochannel.c b/glib/giochannel.c
+index e54aea256..640f698cb 100644
+--- a/glib/giochannel.c
++++ b/glib/giochannel.c
+@@ -1828,7 +1828,8 @@ read_again:
+ {
+ if (channel->line_term)
+ {
+- if (memcmp (channel->line_term, nextchar, line_term_len) == 0)
++ if ((size_t) (lastchar - nextchar) >= line_term_len &&
++ memcmp (channel->line_term, nextchar, line_term_len) == 0)
+ {
+ line_length = nextchar - use_buf->str;
+ got_term_len = line_term_len;
+diff --git a/glib/tests/io-channel.c b/glib/tests/io-channel.c
+index cab486932..3ff5d38e3 100644
+--- a/glib/tests/io-channel.c
++++ b/glib/tests/io-channel.c
+@@ -29,6 +29,7 @@
+
+ #include <glib.h>
+ #include <glib/gstdio.h>
++#include <stdint.h>
+
+ static void
+ test_small_writes (void)
+@@ -228,6 +229,65 @@ test_read_line_embedded_nuls (void)
+ g_free (filename);
+ }
+
++static void
++test_read_line_long_terminator (void)
++{
++ uint8_t *test_data = NULL;
++ size_t test_data_len = 0;
++ int fd;
++ char *filename = NULL;
++ GIOChannel *channel = NULL;
++ GError *local_error = NULL;
++ char *line = NULL;
++ size_t line_length, terminator_pos;
++ const char *line_term;
++ int line_term_length;
++ GIOStatus status;
++
++ g_test_summary ("Test that reading a line when using a long terminator doesn’t over-read the buffer.");
++ g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/work_items/3925");
++
++ /* Write out a temporary file containing 2047 bytes. This is enough to make it
++ * near the length of the GString buffer when read back in. */
++ fd = g_file_open_tmp ("glib-test-io-channel-XXXXXX", &filename, &local_error);
++ g_assert_no_error (local_error);
++ g_close (g_steal_fd (&fd), NULL);
++
++ test_data_len = 2047;
++ test_data = g_malloc (test_data_len);
++ memset (test_data, 'M', test_data_len);
++ g_file_set_contents (filename, (const gchar *) test_data, test_data_len, &local_error);
++ g_assert_no_error (local_error);
++
++ /* Create the channel. */
++ channel = g_io_channel_new_file (filename, "r", &local_error);
++ g_assert_no_error (local_error);
++
++ /* Use a long line terminator so it could potentially over-read the end of the buffer. */
++ g_io_channel_set_line_term (channel, "DEADBEEF", 8);
++
++ line_term = g_io_channel_get_line_term (channel, &line_term_length);
++ g_assert_cmpstr (line_term, ==, "DEADBEEF");
++ g_assert_cmpint (line_term_length, ==, 8);
++
++ g_io_channel_set_encoding (channel, "UTF-8", &local_error);
++ g_assert_no_error (local_error);
++
++ status = g_io_channel_read_line (channel, &line, &line_length,
++ &terminator_pos, &local_error);
++ g_assert_no_error (local_error);
++ g_assert_cmpint (status, ==, G_IO_STATUS_NORMAL);
++ g_assert_cmpuint (line_length, ==, 2047);
++ g_assert_cmpuint (terminator_pos, ==, 2047);
++ g_assert_cmpmem (line, line_length, test_data, test_data_len);
++
++ g_free (line);
++ g_io_channel_unref (channel);
++ g_free (test_data);
++ g_unlink (filename);
++ g_free (filename);
++}
++
+ int
+ main (int argc,
+ char *argv[])
+@@ -236,6 +295,7 @@ main (int argc,
+
+ g_test_add_func ("/io-channel/read-write", test_read_write);
+ g_test_add_func ("/io-channel/read-line/embedded-nuls", test_read_line_embedded_nuls);
++ g_test_add_func ("/io-channel/read-line/long-terminator", test_read_line_long_terminator);
+
+ return g_test_run ();
+ }
+--
+2.35.6
@@ -236,6 +236,7 @@ SRC_URI += "\
file://CVE-2026-58010.patch \
file://CVE-2026-58011.patch \
file://CVE-2026-58012.patch \
+ file://CVE-2026-58013.patch \
"
SRC_URI:append:class-native = " file://relocate-modules.patch \
file://0001-meson.build-do-not-enable-pidfd-features-on-native-g.patch \