# NFSD: Prevent client use-after-free during close_lru reaping

CVE record · `CVE-2026-90037`

- **Identifiers:** `CVE-2026-90037`
- **State:** Confirmed
- **Severity:** CVSS 9.8 Critical
- **Critical:** Yes: CVSS 9+
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 16 Sept 2026
- **Updated:** 30 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 16 Sept 2026, 10:33 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Critical

Critical, because:

- CVSS score 9.8: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected products, as the CNA wrote them

- Vendor: Linux. Product: Linux.
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before 1d721729762a413015864b2a56d7fb86fb8efa9f` (git)
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before adc34b5df5c5d87043cb500b0867fc1c4ad0117e` (git)
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before 0763482227822f7343557f086afc382086d56c4c` (git)
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before 83dd59ac1c3455c2c7d8ddb582d980a13199b9b3` (git)
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1` (git)
  - affected: `217526e7ecc9f6f243e976772e81eab7ab986a4c to before 2330b788d732f43668b965b3105b37ceb276dfea` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `3.17`
  - unaffected: `before 3.17` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.160 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.111 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.51 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.5 to 7.2.*, inclusive` (semver)
  - unaffected: `7.3 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The Linux kernel NFS server (NFSD) is affected from version 3.17. A race during reaping of closed NFSv4 open-owner entries can cause a use-after-free of a client structure. The description gives few details on what an attacker needs to trigger it or what they could gain. Upgrade to 6.1.191, 6.6.160, 6.12.111, or 6.18.51, or a later release in the matching series.

Written 12 Nov 2026.

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

- 9.8 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`, from CNA (Linux)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0051, the 44th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the CVE Program, published 16 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-90037](https://www.cve.org/CVERecord?id=CVE-2026-90037)
- [NVD: CVE-2026-90037](https://nvd.nist.gov/vuln/detail/CVE-2026-90037)

### References from the CNA

- <https://git.kernel.org/stable/c/1d721729762a413015864b2a56d7fb86fb8efa9f>
- <https://git.kernel.org/stable/c/adc34b5df5c5d87043cb500b0867fc1c4ad0117e>
- <https://git.kernel.org/stable/c/0763482227822f7343557f086afc382086d56c4c>
- <https://git.kernel.org/stable/c/83dd59ac1c3455c2c7d8ddb582d980a13199b9b3>
- <https://git.kernel.org/stable/c/e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1>
- <https://git.kernel.org/stable/c/2330b788d732f43668b965b3105b37ceb276dfea>

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-90037>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-90037/>. Everything for agents: <https://agentprime.io/llms.txt>.