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VulnerabilityPublished Updated

CVE-2026-63800: Linux kernel · pNFS: Fix use-after-free in pnfs_update_layout()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in 9645aaf689aff57427ece3b9fa47d5b5399417f4 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in 9645aaf689aff57427ece3b9fa47d5b5399417f4, 2883ddd7542b4437a2ab4908fe2773f690e20889, 200e7637f4d6a1342987045eea72641524f909dc +7
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • >=5.10.9 <5.10.260
  • >=5.4.91 <5.5
Fixed in
  • 9645aaf689aff57427ece3b9fa47d5b5399417f4
  • 2883ddd7542b4437a2ab4908fe2773f690e20889
  • 200e7637f4d6a1342987045eea72641524f909dc
  • 13e198a90ca4050f4bee8a3f23680389a6563ccc
  • 9c0fb5c09ae5bd68dc0038692af8127029cb0385
  • 7e37e9b3e82ade881e1798e2f4fcc54aff7793c1
  • 5.10.260
  • 5.5
  • 4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98
  • 1f24b8302c77dcaf79c64c073877a3b9f4dd25d2
LinuxLinuxAffected
  • =5.11
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix use-after-free in pnfs_update_layout() When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(), the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds, pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(), which still references 'lo'. This results in a use-after-free when the tracepoint accesses lo's fields. Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).

References

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