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Linux KernelOperating system · Linux

CVE-2026-43187

HIGH · 8.8 CVSS v3.1 Published 2026-05-06
Fix available
A fix is available. Upgrade to 5.10.252 / 5.15.202 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.12.1, < 5.10.252>= 5.11, < 5.15.202>= 5.16, < 6.1.165>= 6.2, < 6.6.128>= 6.7, < 6.12.75>= 6.13, < 6.18.16>= 6.19, < 6.19.6= 2.6.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.10.252 / 5.15.202 / 6.1.165 or later
Fixed in 5.10.2525.15.2026.1.165
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to 5.10.252+, 5.15.202+, 6.1.165+, or 6.6.128+ depending on your current branch

  1. 1. Identify the currently running Linux kernel version using `uname -r`
  2. 2. Determine which version range your current kernel falls into (5.10.x, 5.11-5.15.x, 5.16-6.1.x, or 6.2-6.6.x)
  3. 3. For kernels in the 5.10.x branch: upgrade to version 5.10.252 or later
  4. 4. For kernels in the 5.11-5.15.x branch: upgrade to version 5.15.202 or later
  5. 5. For kernels in the 5.16-6.1.x branch: upgrade to version 6.1.165 or later
  6. 6. For kernels in the 6.2-6.6.x branch: upgrade to version 6.6.128 or later
  7. 7. Obtain the kernel update from your Linux distribution's package repositories or kernel.org
  8. 8. Reboot the system into the updated kernel
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom modules or specific hardware drivers

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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Peer-ranked notes from engineers who’ve handled CVE-2026-43187 in production — separate from our analysis above.

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