CVE-2026-68137
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
In the Linux kernel's net/x25 subsystem, there is a use-after-free vulnerability in x25_kill_by_neigh(). The function walks the global X.25 socket list but does not pin the socket's lifetime after dropping the list lock. A concurrent close can free the socket, and the function then uses the freed object. The fix takes a reference with sock_hold() and rechecks the connection.
Risk Assessment
An attacker could cause a kernel panic or potentially gain unauthorized memory access, leading to system compromise.
Recommendation
Apply the Linux kernel patch and reboot the system to mitigate the risk.
Original NVD description (English source)
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().