CVE-2026-68137: In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free in x25_kill_by_neigh() x25_kill_by_neigh() walks the...

Description

In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free in x25_kill_by_neigh() x25_kill_by_neigh() walks the global X.25 socket list looking for sockets attached to a terminating neighbour. x25_list_lock protects list membership while the lookup is in progress, but it does not pin a socket's lifetime after the lock is dropped. The function currently drops x25_list_lock before calling lock_sock(s). A concurrent close can run x25_release(), remove the same socket from x25_list, and drop the last socket reference in that window. The neighbour teardown path can then lock or inspect a freed struct sock/struct x25_sock. Take sock_hold(s) while x25_list_lock still proves that the list entry is live, then drop the temporary reference after the socket has been locked, rechecked, and released. Recheck x25_sk(s)->neighbour after lock_sock(), because another path may have disconnected the socket before this path acquired the socket lock. Restart the list walk after each disconnect because the list lock was dropped and the previous iterator state may no longer be valid. A QEMU/KASAN run against origin/master reproduced a slab-use-after-free in x25_kill_by_neigh().

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 7781607938c8371d4c2b243527430241c62e39c2, < 3f4fe26c20c30bd5a2e2583e80685def0b27858c; >= 7781607938c8371d4c2b243527430241c62e39c2, < 610678d4be94b619c751572e8a58de705592cd07; >= 7781607938c8371d4c2b243527430241c62e39c2, < ec6d91a1bf2ebd767d3d43f6d249ee0ed3f4558a; >= 7781607938c8371d4c2b243527430241c62e39c2, < 9aabda553184346f74810e2ee1d96920b4612e3f; >= 7781607938c8371d4c2b243527430241c62e39c2, < 5499e0602d2faafd42c580d25f615903c3fbe11b; dffc859d1d9560da594e4282091781b8d2715f00; 858642789ada1b48630f322e59416ca9fca3e6b7; 4c240c5a105557e4546d0836e694868f22fd09b0; 9acf05b4e7b55fdb712ef7b331dbce5bcd391d0f; 5c94b6205e87411dbe9dc1ca088eb36b8837fb47; 409570a619c1cda2e0fde6018a256b9e3d3ba0ee; 4a279d7ee1c65411b4055ecd428b8aa2b1711c1f; 671529db75e6be777bb1c76aa07c2bdd2992be6d; >= 4.9.311, < 4.10; >= 4.14.276, < 4.15; >= 4.19.238, < 4.20; >= 5.4.189, < 5.5; >= 5.10.110, < 5.11; >= 5.15.33, < 5.16; >= 5.16.19, < 5.17; >= 5.17.2, < 5.18
Linux	Linux	5.18

References

Timeline

Published: Aug 10, 2026
Last Modified: Aug 10, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-68137?

In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free in x25_kill_by_neigh() x25_kill_by_neigh() walks the global X.25 socket list looking for sockets attached to a terminating neighbour. x25_list_lock protects list membership while the lookup is in progress, but it does not pin a socket's lifetime after the lock is dropped. The function currently drops x25_list_lock before calling lock_sock(s). A concurrent close can run x25_release(), remove the same socket from x25_list, and drop the last socket reference in that window. The neighbour teardown path can then lock or inspect a freed struct sock/struct x25_sock. Take sock_hold(s) while x25_list_lock still proves that the list entry is live, then drop the temporary reference after the socket has been locked, rechecked, and released. Recheck x25_sk(s)->neighbour after lock_sock(), because another path may have disconnected the socket before this path acquired the socket lock. Restart the list walk after each disconnect because the list lock was dropped and the previous iterator state may no longer be valid. A QEMU/KASAN run against origin/master reproduced a slab-use-after-free in x25_kill_by_neigh().

How severe is CVE-2026-68137?

Severity scoring for CVE-2026-68137 is pending analysis.

How do I fix CVE-2026-68137?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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