--- title: "CVE-2026-12666: IBM MQ - XML External Entity Injection" description: "IBM MQ 9.1.0.0 through 9.1.0.37 LTS, 9.2.0.0 through 9.2.0.43 LTS, 9.3.0.0 through 9.3.0.41 LTS, 9.3.0.0 through 9.3.5.1 CD, 9.4.0.0 through 9.4.0.25 LTS, 9.4.0.0 through 9.4.5.1 CD, and 10.0.0.0 Classes for Java contain an XML external entity injection caused by improper MQRFH2 header processing, letting authenticated attackers obtain sensitive information or cause denial of service, exploit requires authentication." url: https://panop.io/threat-heartbeat/CVE-2026-12666/ --- # CVE-2026-12666 IBM MQ - XML External Entity Injection IBM MQ 9.1.0.0 through 9.1.0.37 LTS, 9.2.0.0 through 9.2.0.43 LTS, 9.3.0.0 through 9.3.0.41 LTS, 9.3.0.0 through 9.3.5.1 CD, 9.4.0.0 through 9.4.0.25 LTS, 9.4.0.0 through 9.4.5.1 CD, and 10.0.0.0 Classes for Java contain an XML external entity injection caused by improper MQRFH2 header processing, letting authenticated attackers obtain sensitive information or cause denial of service, exploit requires authentication. CVSS base score 8.1 /10 High CISA KEV Not listed Public exploit None known Authentication Required EPSS 0.26% chance of exploitation in 30 days [View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-12666) ## Details Type XML External Entity Injection Impact Information Disclosure, Denial Of Service CVSS vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H Published 15 September 2026 Updated 15 October 2026 Weakness [CWE-611](https://cwe.mitre.org/data/definitions/611.html) ## Vendor fix Update to the latest available version beyond 10.0.0.0 or apply vendor patches. Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them. ## References - [https://nvd.nist.gov/vuln/detail/CVE-2026-12666](https://nvd.nist.gov/vuln/detail/CVE-2026-12666) - [https://www.ibm.com/support/pages/node/7284939](https://www.ibm.com/support/pages/node/7284939) [← All CVEs](https://panop.io/threat-heartbeat/) ## What this record can't tell you - Whether you run the affected software, and where - Whether an attacker can actually reach and exploit it - The misconfigurations that never get a CVE number - What it would cost the business, ranked into what to fix first Panop answers these inside your environment, for this CVE and every other finding. [Book a demo](https://panop.io/demo)