CVE-2026-12666 IBM MQ Java messaging is vulnerable to XML external entity injection
An authenticated attacker can exploit XML external entity injection in IBM MQ Java messaging to obtain sensitive information or cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-12666?
CVE-2026-12666 is a high-severity vulnerability in IBM MQ, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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 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.
Weakness: CWE-611
Which versions are affected by CVE-2026-12666?
How do I fix CVE-2026-12666?
No fix has been published for CVE-2026-12666 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-12666 being exploited?
There is no known exploitation of CVE-2026-12666 in the wild and no public exploit code.
Sources
Also known as GHSA-8mq2-hm2c-3ccx.