CVE-2026-53309
Description
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.
Statement
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.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.1 | N/A | 9.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | Low | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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