# smb: client: reject a tree connect response whose byte count is too small

CVE record · `CVE-2026-89631`

- **Identifiers:** `CVE-2026-89631`
- **State:** Confirmed
- **Severity:** CVSS 9.1 Critical
- **Critical:** Yes: CVSS 9+
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 11 Sept 2026
- **Updated:** 30 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 11 Sept 2026, 19:45 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 9.1: 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: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before bb99866cb1d3d5e8201200a8692fd8da3106a8fd` (git)
  - affected: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before d837645a719151ed392d4d9cab4571c2753dab12` (git)
  - affected: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before 2ae219762ebac929bf6ab3473681f10ed566af08` (git)
  - affected: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before 3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d` (git)
  - affected: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before 411e484fe71a7f1028de617447edad9cb6d9d68a` (git)
  - affected: `cc20c031bb067eb3280a1c4b5c42295093e24863 to before 65deb18359341141d37dc86fc7853511be3c87a7` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `2.6.30`
  - unaffected: `before 2.6.30` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.160 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.114 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.51 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0049, the 42nd 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-2026-89631](https://www.cve.org/CVERecord?id=CVE-2026-89631)
- [NVD: CVE-2026-89631](https://nvd.nist.gov/vuln/detail/CVE-2026-89631)

### References from the CNA

- <https://git.kernel.org/stable/c/bb99866cb1d3d5e8201200a8692fd8da3106a8fd>
- <https://git.kernel.org/stable/c/d837645a719151ed392d4d9cab4571c2753dab12>
- <https://git.kernel.org/stable/c/2ae219762ebac929bf6ab3473681f10ed566af08>
- <https://git.kernel.org/stable/c/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d>
- <https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a>
- <https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7>

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-2026-89631>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-89631/>. Everything for agents: <https://agentprime.io/llms.txt>.