High [CVE-2026-53309] fix off-by-one in dlm_match_regions region comparison
This high-severity Red Hat Linux advisory covers CVE-2026-53309.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: fix off-by-one in dlm_match_regions() region comparison The local-vs-remote region comparison loop uses '<=' instead of '<', causing it to read one entry past the valid range of qr_regions. The other loops in the same function correctly use '<'.
Fix the loop condition to use '<' for consistency and correctness. A flaw was found in the Linux kernel's OCFS2 Distributed Lock Manager (DLM) component.
This out-of-bounds read could lead to system instability or crashes. The vulnerable code path is reached only on systems using the OCFS2 clustered filesystem, when a node compares its configured resource regions with those reported by a remote node during DLM domain setup.
All Red Hat Enterprise Linux kernel and kernel-rt streams (RHEL 6 ELS through RHEL 10) and Red Hat In-Vehicle OS 2.x kernels are not affected because the vulnerable code is not present in Red Hat's shipped kernels.
The severity assigned by the upstream CVE record (CVSS 9.8, Critical) is higher than Red Hat's assessment (CVSS 7.1, Important); this difference reflects the conservative generic scoring of the upstream record compared with Red Hat's analysis of the specific OCFS2 DLM code path involved. Weakness: CWE-125.
Is CVE-2026-53309 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-53309 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-53309?
The advisory VulniPulse tracks names no fixed release. Follow Red Hat's guidance for workarounds and updates.
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
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