CVE-2026-74628net/x25: fix use-after-free of the socket by its timers
Updated under an hour ago ()
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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 <baul.lee@xbow.com>
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Aug 27, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 6b79659590f0f82a9b8efd2ffd55ec6399ebfc33; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before fdd9ac50b9b61ef2b2d52c5156aff788be91454d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 3c4919be5d910db4beebca420953858606fba7d8; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 4bc522b33438fefc3272840ae5988771863a4f1f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before e92c7e2b41d1528a830bc64c5e4e46dfa8133dda; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 2195424c3da2ef1829a63b807e3a900a90e57d85 | CNA record |
References
- https://git.kernel.org/stable/c/ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8
- https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33
- https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d
- https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6
- https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8
- https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f
- https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda
- https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.