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Vulnerabilities

Vulnerability · CVE-2026-43187

In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf…

Published May 6, 2026 · catalog updated Jun 17, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2026-43187. EPSS is 0.68%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.68%
Remediation
Advisory link
Affected products
cpe linux/linux kernel

In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of the end of the xattr entries array to experience a size underflow when subtracting the space consumed by an expansion of the entries array. There are only three freemap entries, which means that it is not a complete index of all free space in the leaf block. This code can leave behind a zero-length freemap entry with a nonzero base. Subsequent setxattr operations can increase the base up to the point that it overlaps with another freemap entry. This isn't in and of itself a problem because the code in _leaf_add that finds free space ignores any freemap entry with zero size. However, there's another bug in the freemap update code in _leaf_add, which is that it fails to update a freemap entry that begins midway through the xattr entry that was just appended to the array. That can result in the freemap containing two entries with the same base but different sizes (0 for the "pushed-up" entry, nonzero for the entry that's actually tracking free space). A subsequent _leaf_add can then allocate xattr namevalue entries on top of the entries array, leading to data loss. But fixing that is for later. For now, eliminate the possibility of confusion by zeroing out the base of any freemap entry that has zero size. Because the freemap is not intended to be a complete index of free space, a subsequent failure to find any free space for a new xattr will trigger block compaction, which regenerates the freemap. It looks like this bug has been in the codebase for quite a long time.

Are you affected?

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  • cpe linux/linux kernel2.6.12

How to fix CVE-2026-43187

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-43187. EPSS is 0.68%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel 2.6.12. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-191: Integer Underflow. EPSS 0.68%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 6, 2026 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of the end of the xattr entries array to experience a size underflow when subtracting the space consumed by an expansion of the

  2. Jun 17, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of the end of the xattr entries array to experience a size underflow when subtracting the space consumed by an expansion of the

Sources

  • CVE.orgVulnerability recordCVE-2026-43187

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-43187

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-43187

    In the Linux kernel, the following vulnerability has been resolved: xfs: delete attr leaf freemap entries when empty Back in commit 2a2b5932db6758 ("xfs: fix attr leaf header freemap.size underflow"), Brian Foster observed that it's possible for a small freemap at the end of th

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.