# CVE-2026-46538: Microsoft UFO Task Result Injection in Constellation Client

Source: https://junglewise.ai/threats/cve-2026-46538-microsoft-ufo-task-result-injection-in-constellation-client  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-27. Updated: 2026-05-27  
License: CC BY 4.0 with a link back

CVE-2026-46538 · Severity: medium · CVSS 5.9 · Published 2026-05-27

Microsoft UFO is an open-source framework used for automating tasks across different devices and platforms. A security flaw allows an authenticated user on one device to intercept and replace the results of tasks intended for a different device. This could lead to the automation system receiving and acting upon fraudulent data, potentially disrupting operations or compromising the integrity of automated workflows.

Technologies: [Microsoft UFO](https://junglewise.ai/threats/technologies/ufo). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-46538 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-46538 being exploited in the wild.

**How severe is CVE-2026-46538?** Medium severity, with a CVSS score of 5.9, published 27 May 2026.

**Which products and versions are affected?** Microsoft UFO 3.0.1-4-ge2626659.

**Is there a fix for CVE-2026-46538?** 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-2026-46538 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-46538?** Check whether you run Microsoft UFO 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

The vulnerability exists in the Microsoft UFO constellation client's task tracking logic within 'connection_manager.py' and 'message_processor.py'. While the system records the expected device ID when a task is initiated, the completion path only validates the 'session_id' of incoming 'TASK_END' messages. An attacker with authenticated access to a peer device can send a forged 'TASK_END' message containing a known 'session_id'. Because the 'complete_task_response' function ignores the binding between the task and the original target device, it accepts the attacker's data and resolves the pending task's Future with the spoofed result. This is classified as an authenticated cross-device task-result injection issue.

## Affected products

- Microsoft UFO (pip) 3.0.1-4-ge2626659

## Timeline

- 2026-05-15: advisory: GitHub Security Advisory published
- 2026-05-27: disclosed: NVD publication date

## References

- [https://github.com/microsoft/UFO/security/advisories/GHSA-wmq2-74rj-7pjc](https://github.com/microsoft/UFO/security/advisories/GHSA-wmq2-74rj-7pjc)

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