CyberSecBulletin
CVE-2026-53043NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-53043 is a critical-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions d3d5efade0c79dac1cac98c0cb1115432f804439, f69551139caf6d24242a0ad049ee46b264e3aee0, 1f8b91275912cd428289c1fb424bebd7ff5302bd as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.51% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to d3d5efade0c79dac1cac98c0cb1115432f804439 or f69551139caf6d24242a0ad049ee46b264e3aee0 or 1f8b91275912cd428289c1fb424bebd7ff5302bd or f37de46149db49abd2b24f4f0c5a88cf4dfb5f47, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.141, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, d3d5efade0c79dac1cac98c0cb1115432f804439; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, f69551139caf6d24242a0ad049ee46b264e3aee0; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, 1f8b91275912cd428289c1fb424bebd7ff5302bd; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, f37de46149db49abd2b24f4f0c5a88cf4dfb5f47; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, 6c6e8fc3c007319981647b410c29bb5775048551; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, 3f474c33ebc2e2ca3fcb587d7de4375348f13373; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, 3c2d0de23ae4be22b6c18e8f0915be74d3b5fb21; ea2034416b54700e30371f2ad6517cbb94674083 up to, but not including, 7ab3fbb01bc6d79091bc375e5235d360cd9b78be; and 1 more rangesd3d5efade0c79dac1cac98c0cb1115432f804439, f69551139caf6d24242a0ad049ee46b264e3aee0, 1f8b91275912cd428289c1fb424bebd7ff5302bd, f37de46149db49abd2b24f4f0c5a88cf4dfb5f47, 6c6e8fc3c007319981647b410c29bb5775048551, 3f474c33ebc2e2ca3fcb587d7de4375348f13373
LinuxLinux Kernel2.6.37 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.105.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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