Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-53265

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Main Vulnerability Database Vulnerabilities #VU135487

Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-53265

Published: June 26, 2026


Vulnerability identifier: #VU135487
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53265
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 a check-then-act race condition in smq_invalidate_mapping() in the dm-cache-policy-smq component when invalidating cache blocks concurrently. A local user can trigger concurrent invalidation operations to cause a denial of service.

The issue can corrupt the SMQ queues or hash table and may result in a double free condition.


Affected software

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

How to mitigate CVE-2026-53265

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13

External References

Related Security Bulletins