CVE-2026-12666: IBM Mq

High severity, CVSS 8.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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 could allow an authenticated attacker to obtain sensitive information or cause a denial of service due to XML external entity injection in MQRFH2 header processing.

Affected products

• IBM Mq: from 9.1.0.0, up to and including 9.1.0.37 LTS; from 9.2.0.0, up to and including 9.2.0.43 LTS; from 9.3.0.0, up to and including 9.3.0.41 LTS; from 9.3.0.0, up to and including 9.3.5.1 CD; from 9.4.0.0, up to and including 9.4.0.25 LTS; from 9.4.0.0, up to and including 9.4.5.1 CD; …

Published 2026-09-15. Last modified 2026-09-17.