Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-99245
Published: November 3, 2026
Vulnerability identifier: #VU158997
CSH Severity: Low
CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-99245
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to bypass a keyring restriction and link a rejected key into the keyring.
The vulnerability exists due to a time-of-check time-of-use race condition in key_reject_and_link() when checking keyring restrictions before acquiring the keyring semaphore. A local user can race a key rejection and linking operation against a concurrent keyring_restrict() operation to link a rejected key despite a newly installed restriction.
Affected software
Linux kernel
How to mitigate CVE-2026-99245
Install security update from vendor's repository.
External References
- https://git.kernel.org/stable/c/01835d3a3709be508ae5209f806640336c48e395
- https://git.kernel.org/stable/c/19dfc37c9deefa69dc805d01d35d1f2fd7902e33
- https://git.kernel.org/stable/c/23a9163cc40b4996ba1e20533b1210a1a0bee416
- https://git.kernel.org/stable/c/2c3d907dd15f4e30d4c35b9f7a7a5078de6a1b1f
- https://git.kernel.org/stable/c/5787887eba0f0979a8c86d03a8e891395d5c24ad
- https://git.kernel.org/stable/c/6fc0c818b1cac66003e937c8a0d3bfb23fd3f130
- https://git.kernel.org/stable/c/72f367417a6aee56821d0b0114cfd2b080008b63
- https://git.kernel.org/stable/c/c7956ec99ad0e173720d95de9fa788bb077809f2