# smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2

CVE record · `CVE-2026-89637`

- **Identifiers:** `CVE-2026-89637`
- **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, 19:45 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 9.8: 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: `316cf94a910f6f93d43cc574359d163ccae098a3 to before 9eed72e9534b10a6d9f8f5146feff3db53aebdba` (git)
  - affected: `316cf94a910f6f93d43cc574359d163ccae098a3 to before 5e6533a683f6a851158d9f33fb4ea8f4f25d7f84` (git)
  - affected: `316cf94a910f6f93d43cc574359d163ccae098a3 to before 730d0bb19507b9e19c2fe5343109ac618e2fbce5` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `3.6`
  - unaffected: `before 3.6` (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

- 9.8 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:** 0.0060, the 49th 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-2026-89637](https://www.cve.org/CVERecord?id=CVE-2026-89637)
- [NVD: CVE-2026-89637](https://nvd.nist.gov/vuln/detail/CVE-2026-89637)

### References from the CNA

- <https://git.kernel.org/stable/c/9eed72e9534b10a6d9f8f5146feff3db53aebdba>
- <https://git.kernel.org/stable/c/5e6533a683f6a851158d9f33fb4ea8f4f25d7f84>
- <https://git.kernel.org/stable/c/730d0bb19507b9e19c2fe5343109ac618e2fbce5>

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-2026-89637>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-89637/>. Everything for agents: <https://agentprime.io/llms.txt>.