CVE-2026-53043: Linux Kernel buffer overflow (CVSS 9.1)

Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: validate qr_numregions in dlm_match_regions() Patch series "ocfs2/dlm: fix two bugs in dlm_match_regions()". In dlm_match_regions(), the qr_numregions field from a DLM_QUERY_REGION network message is used to drive loops over the qr_regions buffer without sufficient validation. This series fixes two issues: - Patch 1 adds a bounds check to reject messages where qr_numregions exceeds O2NM_MAX_REGIONS. The o2net layer only validates message byte length; it does not constrain field values, so a crafted message can set qr_numregions up to 255 and trigger out-of-bounds reads past the 1024-byte qr_regions buffer. - Patch 2 fixes an off-by-one in the local-vs-remote comparison loop, which uses '<=' instead of '<', reading one entry past the valid range even when qr_numregions is within bounds. This patch (of 2): The qr_numregions field from a DLM_QUERY_REGION network message is used directly as loop bounds in dlm_match_regions() without checking against O2NM_MAX_REGIONS. Since qr_regions is sized for at most O2NM_MAX_REGIONS (32) entries, a crafted message with qr_numregions > 32 causes out-of-bounds reads past the qr_regions buffer. Add a bounds check for qr_numregions before entering the loops.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

Linux Kernel≥ 2.6.37 < 5.10.258 · ≥ 5.11 < 5.15.209 · ≥ 5.16 < 6.1.175 · ≥ 6.13 < 6.18.33

Remediation

Fixed in

Linux Kernel≥ 5.10.258

Patch & vendor advisories

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-53043 being actively exploited?

CVE-2026-53043 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.73%.

How severe is CVE-2026-53043?

CVE-2026-53043 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.73% probability of exploitation.

Which products are affected by CVE-2026-53043?

Affected products include Linux Kernel.

How do I fix CVE-2026-53043?

Upgrade affected software to a fixed version, for example Linux Kernel 5.10.258 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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