# CVE-2026-11727: IBM MQ for HPE NonStop C client heap overflow in AMS policy handling

Source: https://junglewise.ai/threats/cve-2026-11727-ibm-mq-for-hpe-nonstop-8-1-0-through-8-1-0-40-ibm-mq-c-client  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-11727 · Severity: high · CVSS 8.1 · Published 2026-09-18

IBM MQ is a messaging middleware used by enterprises to route business-critical transactions and data between applications. The C client component fails to validate responses from queue managers when processing AMS security policy data, allowing a remote attacker to trigger a heap buffer overflow. This can cause the client application to crash (denial of service) or execute arbitrary code on the system running the client.

Technologies: [IBM MQ for HPE NonStop](https://junglewise.ai/threats/technologies/mq-for-hpe-nonstop). Vendors: [IBM](https://junglewise.ai/threats/vendors/ibm).

## Quick answers

**Is CVE-2026-11727 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-11727 being exploited in the wild.

**How severe is CVE-2026-11727?** High severity, with a CVSS score of 8.1, published 18 September 2026.

**Which products and versions are affected?** IBM MQ for HPE NonStop 8.1.0 through 8.1.0.40.

**Is there a fix for CVE-2026-11727?** A patch was published on 2026-09-17: CSU 8.1.0.41 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-11727 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-11727?** Check whether you run IBM MQ for HPE NonStop 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.

## Technical details

A heap-based buffer overflow exists in the IBM MQ C client's handling of queue manager responses during AMS (Application Messaging Services) policy data requests due to improper input validation. The vulnerability is remotely exploitable over the network with no authentication or user interaction required, affecting versions 8.1.0 through 8.1.0.40. A patched version 8.1.0.41 is available.

## Affected products

- IBM MQ for HPE NonStop 8.1.0 through 8.1.0.40

## Timeline

- 2026-09-17: disclosed
- 2026-09-17: patched: CSU 8.1.0.41 released

## References

- [https://www.ibm.com/support/pages/node/7287708](https://www.ibm.com/support/pages/node/7287708)

## Related threats

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