# KVM: s390: Fix memory corruption by not reinjecting CK machine checks

CVE record · `CVE-2026-89920`

- **Identifiers:** `CVE-2026-89920`
- **State:** Confirmed
- **Severity:** CVSS 7.8 High
- **Critical:** No
- **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, 10:32 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.

## Affected products, as the CNA wrote them

- Vendor: Linux. Product: Linux.
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before 045f3e95a0deccb277c29bd003e1d43c0ad40c90` (git)
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before 5c63e2ed840c85e27172ab78e7db3ac77fba281b` (git)
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before b7631982fb65dd355acd18e62b384bc8125e9c44` (git)
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before 6ee52d3af2a1bf70349cf3f860933c8d221e229a` (git)
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before 7077ec953996acc04b49d1dfc43df1c1a2a74395` (git)
  - affected: `4d62fcc0b692e3b4058d7d138114c27cd8b011f7 to before 546dde823a36d7283dcf46127c2f3d093443860f` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `4.13`
  - unaffected: `before 4.13` (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: `7.2.5 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.

> KVM for s390 in the Linux kernel, from 4.13 until fixed, can suffer memory corruption from reinjected channel-subsystem machine checks. The source gives few details on what an attacker needs. Upgrade to Linux 6.1.191, 6.6.160, 6.12.114, 6.18.51, or a later stable release in those 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0018, the 7th percentile, on 15 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-2026-89920](https://www.cve.org/CVERecord?id=CVE-2026-89920)
- [NVD: CVE-2026-89920](https://nvd.nist.gov/vuln/detail/CVE-2026-89920)

### References from the CNA

- <https://git.kernel.org/stable/c/045f3e95a0deccb277c29bd003e1d43c0ad40c90>
- <https://git.kernel.org/stable/c/5c63e2ed840c85e27172ab78e7db3ac77fba281b>
- <https://git.kernel.org/stable/c/b7631982fb65dd355acd18e62b384bc8125e9c44>
- <https://git.kernel.org/stable/c/6ee52d3af2a1bf70349cf3f860933c8d221e229a>
- <https://git.kernel.org/stable/c/7077ec953996acc04b49d1dfc43df1c1a2a74395>
- <https://git.kernel.org/stable/c/546dde823a36d7283dcf46127c2f3d093443860f>

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-2026-89920>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

---

The web page: <https://agentprime.io/advisories/CVE-2026-89920/>. Everything for agents: <https://agentprime.io/llms.txt>.