# CVE-2026-12538: IBM MQ Appliance is affected by an improper validation vulnerability

Status: published. Published: 2026-11-04. Updated: 2026-11-09.

IBM MQ 9.4.0.0 to 9.4.0.26, 9.4.1.0 to 9.4.5.3, and 10.0.0.1 to 10.0.0.5 could allow an authenticated attacker to obtain sensitive information or cause a denial of service due to improper validation of message header structure length fields.

## Remediation

- fix: This vulnerability is addressed under APAR DT500605.



IBM strongly recommends addressing the vulnerability now.



IBM MQ Appliance version 9.4 LTS
Apply  IBM MQ Appliance fix pack 9.4.0.30 https://www.ibm.com/support/fixcentral/swg/selectFixes , or later firmware.



IBM MQ Appliance version 9.4 CD - M2003
Upgrade to  IBM MQ Appliance 10.0.0.6 https://www.ibm.com/support/fixcentral/swg/selectFixes , or later firmware.



IBM MQ Appliance version 9.4 CD - M2002
Apply  IBM MQ Appliance cumulative security update 9.4.5.4 https://www.ibm.com/support/fixcentral/swg/selectFixes , or later firmware.



IBM MQ Appliance version 10 LTS
Apply  IBM MQ Appliance cumulative security update 10.0.0.6 https://www.ibm.com/support/fixcentral/swg/selectFixes , or later firmware. (source: CNA: ibm)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: ibm) — https://www.ibm.com/support/pages/node/7293035

## Affected products and versions

- IBM / MQ Appliance: ≥ 9.4.0.0; ≤ 9.4.0.26 (affected, semver); ≥ 9.4.1.0; ≤ 9.4.5.3 (affected, semver); ≥ 10.0.0.1; ≤ 10.0.0.5 (affected, semver). Source: CNA: ibm

## Severity and prioritization

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L; source: CNA: ibm

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L; source: NVD: psirt@us.ibm.com

- CISA KEV: No listing in collected sources

- EPSS: 0.33% as of 2026-11-09; percentile 26.71%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-124

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.ibm.com/support/pages/node/7293035 (CNA: ibm; vendor-advisory, patch)

- https://www.ibm.com/support/pages/node/7293035 (psirt@us.ibm.com)

## Provenance

- CNA: ibm: https://www.cve.org/CVERecord?id=CVE-2026-12538; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12538; retrieved 2026-11-05; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-12538; retrieved 2026-11-09; source updated Not reported

Revision: 4fba36d103cd0199836b086e6bcb2c1fb629e64668aca0b98ba1a570ec430fe2

Canonical: https://y2.dev/cve/CVE-2026-12538

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.