# CVE-2026-34329: Microsoft Windows Message Queuing heap overflow

Source: https://junglewise.ai/threats/cve-2026-34329-microsoft-windows-message-queuing-heap-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-05-14  
License: CC BY 4.0 with a link back

CVE-2026-34329 · Severity: high · CVSS 8.8 · Published 2026-05-12

A security vulnerability exists in Windows Message Queuing, a service used by applications to communicate reliably across networks. An attacker located on the same local network could exploit this flaw to take full control of an affected system without needing any login credentials. This could lead to the theft of sensitive data, disruption of business operations, or the installation of malicious software.

Technologies: [Microsoft Windows Message Queuing](https://junglewise.ai/threats/technologies/windows-message-queuing). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-34329 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34329 being exploited in the wild.

**How severe is CVE-2026-34329?** High severity, with a CVSS score of 8.8, published 12 May 2026.

**Which products and versions are affected?** Microsoft Windows Message Queuing (MSMQ).

**Is there a fix for CVE-2026-34329?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-34329 attacked?** It is attacked from the adjacent network, in an operating system.

**Am I affected by CVE-2026-34329?** Check whether you run Microsoft Windows Message Queuing. 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 (CWE-122) exists in the Microsoft Windows Message Queuing (MSMQ) service. The vulnerability is triggered when the service improperly handles specially crafted network packets, leading to memory corruption. An unauthenticated attacker located on the same subnet or local network (Adjacent vector) can exploit this to achieve remote code execution with high privileges. No user interaction is required for successful exploitation. Microsoft has released security updates to address this issue via the MSRC update guide.

## Affected products

- Microsoft Windows Message Queuing (MSMQ)

## Timeline

- 2026-05-12: disclosed
- 2026-05-12: advisory: Microsoft published the security update guide.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34329](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34329)

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