CVE-2026-53309

A flaw was found in the Linux kernel's OCFS2 Distributed Lock Manager (DLM) component. An off-by-one error in the dlm_match_regions() function's region comparison loop causes it to read beyond the valid memory range of qr_regions. This out-of-bounds read could lead to system instability or crashes.

An out-of-bounds read flaw of important impact was found in the Linux kernel's OCFS2 Distributed Lock Manager (DLM). In dlm_match_regions(), the loop that compares local and remote resource regions uses '<=' instead of '<', causing it to read one entry past the valid range of the qr_regions array. 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.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.