CVE-2026-53309: ocfs2/dlm: fix off-by-one in dlm_match_regions() region comparison

criticalCVSS 9.8CVE-2026-53309

CSIRTS triage

Privilege escalation

What: An off-by-one error in region comparison can lead to privilege escalation.
Who is affected: Deployments using ocfs2/dlm are affected.
Urgency: Remediation is critical due to the high severity and potential for exploitation.
Action: Patch the affected systems immediately.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: critical — CVSS 9.8
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53309

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-533090.40% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 32% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-53309	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for ocfs2/dlm

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

criticalCVE-2026-53309: In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: fix off-by-one …nvd · 2026-06-26
criticalCVE-2026-53043: ocfs2/dlm: validate qr_numregions in dlm_match_regions()msrc · 2026-06-09