# smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()

CVE record · `CVE-2026-89633`

- **Identifiers:** `CVE-2026-89633`
- **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:** 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 9.8: 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: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before f7baf60435129e3a5f3500a38e3cb4c3860deed7` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 9f3a7440731a34c89ad04fef6616f185acb28401` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 531ac35abd74fb5b4aec5e19543e832613a1789d` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 6eb70b78e48b0031bd1a05fe1b58959a48e87739` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 36d01415d881d5326a0dd3384f781cd7e69aff2d` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 033bc80019f07d158630df4e69b19a49010f54f1` (git)
  - affected: `e4eb295d38b57f4d4b956942a48887eb252d97c6 to before 6343c1da561962688f203362d80d6a3bfa39fa1b` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `2.6.12`
  - unaffected: `before 2.6.12` (semver)
  - unaffected: `5.10.273 to 5.10.*, inclusive` (semver)
  - unaffected: `5.15.224 to 5.15.*, inclusive` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.160 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.113 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

- 9.8 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:** 0.0055, the 46th 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-2026-89633](https://www.cve.org/CVERecord?id=CVE-2026-89633)
- [NVD: CVE-2026-89633](https://nvd.nist.gov/vuln/detail/CVE-2026-89633)

### References from the CNA

- <https://git.kernel.org/stable/c/f7baf60435129e3a5f3500a38e3cb4c3860deed7>
- <https://git.kernel.org/stable/c/9f3a7440731a34c89ad04fef6616f185acb28401>
- <https://git.kernel.org/stable/c/531ac35abd74fb5b4aec5e19543e832613a1789d>
- <https://git.kernel.org/stable/c/6eb70b78e48b0031bd1a05fe1b58959a48e87739>
- <https://git.kernel.org/stable/c/36d01415d881d5326a0dd3384f781cd7e69aff2d>
- <https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e>
- <https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1>
- <https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b>

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-2026-89633>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-89633/>. Everything for agents: <https://agentprime.io/llms.txt>.