CVE-2026-74628
net/x25: fix use-after-free of the socket by its timers
Description
In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free of the socket by its timers The x25 timers are armed with mod_timer() and cancelled with timer_delete(), so a pending timer holds no reference on the socket and a cancel does not wait for a callback already running on another CPU. x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall sk->sk_timer after __x25_destroy_socket() has passed its cancel point. The following __sock_put() frees the socket while the timer is still queued, and the next expiry uses freed memory. KASAN reports a slab-use-after-free on the kmalloc-2k object freed by close(). timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and x25_timer_expiry() both reach the cancels from inside the timer they would wait on, through __x25_destroy_socket() and x25_disconnect(). Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer() so that an armed timer owns a reference, and release it in both expiry handlers. Rearm the heartbeat only while sk_hashed(sk) is still true, since __x25_destroy_socket() unlinks the socket before dropping it. Arm the deferred destroy timer the same way and drop its reference in x25_destroy_timer(). Reproduced on net with KASAN, with the heartbeat period shortened so the window recurs. With this patch the reproducer no longer triggers a report and /proc/net/x25 drains. Discovered by XBOW, triaged by Baul Lee <[email protected]>
INFO
Published Date :
Aug. 22, 2026, 4:16 p.m.
Last Modified :
Aug. 27, 2026, 1:18 p.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Arm timers with sk_reset_timer() and cancel with sk_stop_timer().
- Release timer reference in expiry handlers.
- Rearm heartbeat only if sk_hashed(sk) is true.
- Arm deferred destroy timer and drop reference in x25_destroy_timer().
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-74628.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-74628 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-74628
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-74628 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-74628 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 27, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/74xxx/CVE-2026-74628.json">CVE-2026-74628</a> Added Reference https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6 Added Reference https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85 Added Reference https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8 Added Reference https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f Added Reference https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33 Added Reference https://git.kernel.org/stable/c/ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8 Added Reference https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda Added Reference https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d Removed Reference https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6 Removed Reference https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85 Removed Reference https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8 Removed Reference https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f Removed Reference https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33 Removed Reference https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda Removed Reference https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 25, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 23, 2026
Action Type Old Value New Value Added Reference https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6 Added Reference https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8 Added Reference https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33 Added Reference https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '4bc522b33438fefc3272840ae5988771863a4f1f', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': 'e92c7e2b41d1528a830bc64c5e4e46dfa8133dda', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '2195424c3da2ef1829a63b807e3a900a90e57d85', 'versionType': 'git'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.45', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.9', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '6b79659590f0f82a9b8efd2ffd55ec6399ebfc33', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': 'fdd9ac50b9b61ef2b2d52c5156aff788be91454d', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '3c4919be5d910db4beebca420953858606fba7d8', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '4bc522b33438fefc3272840ae5988771863a4f1f', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': 'e92c7e2b41d1528a830bc64c5e4e46dfa8133dda', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '2195424c3da2ef1829a63b807e3a900a90e57d85', 'versionType': 'git'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.15.217', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.184', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.153', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.105', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.45', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.9', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 22, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '4bc522b33438fefc3272840ae5988771863a4f1f', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': 'e92c7e2b41d1528a830bc64c5e4e46dfa8133dda', 'versionType': 'git'}, {'status': 'affected', 'version': '1da177e4c3f41524e886b7f1b8a0c1fc7321cac2', 'lessThan': '2195424c3da2ef1829a63b807e3a900a90e57d85', 'versionType': 'git'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.45', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.9', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/x25/af_x25.c', 'net/x25/x25_timer.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free of the socket by its timers The x25 timers are armed with mod_timer() and cancelled with timer_delete(), so a pending timer holds no reference on the socket and a cancel does not wait for a callback already running on another CPU. x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall sk->sk_timer after __x25_destroy_socket() has passed its cancel point. The following __sock_put() frees the socket while the timer is still queued, and the next expiry uses freed memory. KASAN reports a slab-use-after-free on the kmalloc-2k object freed by close(). timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and x25_timer_expiry() both reach the cancels from inside the timer they would wait on, through __x25_destroy_socket() and x25_disconnect(). Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer() so that an armed timer owns a reference, and release it in both expiry handlers. Rearm the heartbeat only while sk_hashed(sk) is still true, since __x25_destroy_socket() unlinks the socket before dropping it. Arm the deferred destroy timer the same way and drop its reference in x25_destroy_timer(). Reproduced on net with KASAN, with the heartbeat period shortened so the window recurs. With this patch the reproducer no longer triggers a report and /proc/net/x25 drains. Discovered by XBOW, triaged by Baul Lee <[email protected]> Added Reference https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85 Added Reference https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f Added Reference https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda