# CVE-2026-12550: IBM MQ heap buffer overflow in message selection validation

Source: https://junglewise.ai/threats/cve-2026-12550-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-04. Updated: 2026-11-04  
License: CC BY 4.0 with a link back

CVE-2026-12550 · Severity: medium · CVSS 5.4 · Published 2026-11-04

IBM MQ is a message queuing middleware platform used by enterprises to integrate applications and systems. An authenticated attacker can exploit improper validation of message selection parameters to either extract sensitive data from the message queue or crash the service, causing business disruption.

Technologies: [IBM Mq](https://junglewise.ai/threats/technologies/mq). Vendors: [IBM](https://junglewise.ai/threats/vendors/ibm).

## Quick answers

**Is CVE-2026-12550 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12550 being exploited in the wild.

**How severe is CVE-2026-12550?** Medium severity, with a CVSS score of 5.4, published 4 November 2026.

**Which products and versions are affected?** IBM Mq 10.0.0.0 through 10.0.0.5 LTS and CD.

**Is there a fix for CVE-2026-12550?** Yes: fixed in MQ 9.2.0.46 LTS, 9.3.0.43 LTS, 9.4.0.30 LTS, 10.0.0.6 LTS, 10.0.1.0 CD. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-12550 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-12550?** Check whether you run IBM Mq at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in MQ 9.2.0.46 LTS, 9.3.0.43 LTS, 9.4.0.30 LTS, 10.0.0.6 LTS, 10.0.1.0 CD

## Technical details

A heap-based buffer overflow exists in IBM MQ's message selection parameter validation (CWE-122). The vulnerability requires prior authentication and network access to the MQ server. An attacker can trigger the overflow to leak memory contents or trigger a denial of service; fixes are available in the versions listed below.

## Affected products

- IBM MQ 9.2.0.0 through 9.2.0.44 LTS
- IBM MQ 9.3.0.0 through 9.3.0.42 LTS
- IBM MQ 9.4.0.0 through 9.4.0.26 LTS
- IBM MQ 9.4.0.0 through 9.4.5.1 CD
- IBM MQ 10.0.0.0 through 10.0.0.5 LTS and CD

## Timeline

- 2026-10-29: disclosed

## References

- [https://www.ibm.com/support/pages/node/7294502](https://www.ibm.com/support/pages/node/7294502)

## Related threats

- [IBM MQ integer overflow in malformed MQINQ request](https://junglewise.ai/threats/cve-2026-18142-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts)
- [IBM MQ password disclosure in log files](https://junglewise.ai/threats/cve-2026-14252-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts)
- [IBM MQ Managed File Transfer arbitrary code execution via environment variables](https://junglewise.ai/threats/cve-2026-13292-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts)
- [IBM MQ XML external entity injection in Managed File Transfer](https://junglewise.ai/threats/cve-2026-13289-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts)
- [IBM MQ XML external entity injection in Managed File Transfer](https://junglewise.ai/threats/cve-2026-13284-ibm-mq-9-2-0-0-through-9-2-0-44-lts-9-3-0-0-through-9-3-0-42-lts)