# SUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow

CVE record · `CVE-2026-89551`

- **Identifiers:** `CVE-2026-89551`
- **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:** 11 Sept 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 11 Sept 2026, 19:44 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: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before a3d77bcd974b8625d16bddf448cb3a1b5e37049c` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before fa16bbe987b47e771e52eeb1b4540f18d92496ac` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before a924ac4c78afab71bf82641afa3b62e0c4a8b55e` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before 4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before e6267cccd7b05cc514e57f2160aa8db85f5c2701` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before ad0cce80d4af2f74674e8b635d97aa3880e83da8` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before 85e9602650e9df07190abe817cee3b4d9bc3df17` (git)
  - affected: `4c190e2f913f038c9c91ee63b59cd037260ba353 to before 3f491306dcb673ff5e78e1044ba450c58978774e` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `3.9`
  - unaffected: `before 3.9` (semver)
  - unaffected: `5.10.270 to 5.10.*, inclusive` (semver)
  - unaffected: `5.15.221 to 5.15.*, inclusive` (semver)
  - unaffected: `6.1.188 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.157 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.109 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.50 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.4 to 7.2.*, inclusive` (semver)
  - unaffected: `7.3 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## 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 14 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 11 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-89551](https://www.cve.org/CVERecord?id=CVE-2026-89551)
- [NVD: CVE-2026-89551](https://nvd.nist.gov/vuln/detail/CVE-2026-89551)

### References from the CNA

- <https://git.kernel.org/stable/c/a3d77bcd974b8625d16bddf448cb3a1b5e37049c>
- <https://git.kernel.org/stable/c/fa16bbe987b47e771e52eeb1b4540f18d92496ac>
- <https://git.kernel.org/stable/c/a924ac4c78afab71bf82641afa3b62e0c4a8b55e>
- <https://git.kernel.org/stable/c/4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4>
- <https://git.kernel.org/stable/c/e6267cccd7b05cc514e57f2160aa8db85f5c2701>
- <https://git.kernel.org/stable/c/ad0cce80d4af2f74674e8b635d97aa3880e83da8>
- <https://git.kernel.org/stable/c/85e9602650e9df07190abe817cee3b4d9bc3df17>
- <https://git.kernel.org/stable/c/3f491306dcb673ff5e78e1044ba450c58978774e>

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-2026-89551>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-89551/>. Everything for agents: <https://agentprime.io/llms.txt>.