Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-64425
Published: July 27, 2026
Vulnerability identifier: #VU139520
CSH Severity: Low
CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64425
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper state management in io_worker_handle_work() in io_uring/io-wq.c when processing linked work items during io_uring worker exit handling. A local user can submit linked work and trigger ring closure to cause a denial of service.
Exploitation requires a race condition where worker exit begins after the first linked item has started but before the remaining linked items are processed.
Affected software
Linux kernel
How to mitigate CVE-2026-64425
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/14b7ecad2ec56699325180a744f4b19f046401bb
- https://git.kernel.org/stable/c/1636d85dc139b07c0449308f2bb5e0c7a2e0da99
- https://git.kernel.org/stable/c/29bef9934b2521f787bb15dd1985d4c0d12ae02a
- https://git.kernel.org/stable/c/6e2f51f3e06773c2ee98ad09738f0908b48f76f9
- https://git.kernel.org/stable/c/ab85765cbe3258b43dc6729af0e6ce3a87a133d8
- https://git.kernel.org/stable/c/b6f179a653a934736c88d820fe0098c3c2532549
- https://git.kernel.org/stable/c/d179533c610e1b4c6aa436e3c1fd1b719d2c727c
- https://git.kernel.org/stable/c/ea61b04e1d7242cb37f5ed2cc91cf21a493f6597