CVE-2026-63800: Linux kernel · pNFS: Fix use-after-free in pnfs_update_layout()
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98 (opens in a new tab)
- git.kernel.org/stable/c/1f24b8302c77dcaf79c64c073877a3b9f4dd25d2 (opens in a new tab)
- git.kernel.org/stable/c/9c0fb5c09ae5bd68dc0038692af8127029cb0385 (opens in a new tab)
- git.kernel.org/stable/c/7e37e9b3e82ade881e1798e2f4fcc54aff7793c1 (opens in a new tab)
- git.kernel.org/stable/c/2883ddd7542b4437a2ab4908fe2773f690e20889 (opens in a new tab)
- git.kernel.org/stable/c/200e7637f4d6a1342987045eea72641524f909dc (opens in a new tab)
- git.kernel.org/stable/c/9645aaf689aff57427ece3b9fa47d5b5399417f4 (opens in a new tab)
- git.kernel.org/stable/c/13e198a90ca4050f4bee8a3f23680389a6563ccc (opens in a new tab)