CVE-2026-46538

CVE-2026-46538 is a medium-severity vulnerability with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-294.

Key facts

Description

Microsoft UFO open-source framework for intelligent automation across devices and platforms. In 3.0.1-4-ge2626659, Microsoft UFO's constellation client tracks pending task responses by session_id only and does not verify that a TASK_END message came from the device that originally received the task. When the constellation sends a task to a target device, it records a pending Future under a session key. The pending task record stores the expected device ID, but the completion path ignores that binding. If another authenticated peer device sends a forged TASK_END with the same session_id, the constellation accepts the response and completes the victim device's pending Future with attacker-controlled result data. This is an authenticated cross-device task-result injection issue.

Frequently asked questions

What is CVE-2026-46538?
Microsoft UFO open-source framework for intelligent automation across devices and platforms. In 3.0.1-4-ge2626659, Microsoft UFO's constellation client tracks pending task responses by session_id only and does not verify that a TASK_END message came from the device that originally received the task. When the constellation sends a task to a target device, it records a pending Future under a session key. The pending task record stores the expected device ID, but the completion path ignores that binding. If another authenticated peer device sends a forged TASK_END with the same session_id, the constellation accepts the response and completes the victim device's pending Future with attacker-controlled result data. This is an authenticated cross-device task-result injection issue.
How severe is CVE-2026-46538?
CVE-2026-46538 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability low.
Is CVE-2026-46538 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-46538?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-46538 have an EU (EUVD) identifier?
Yes. CVE-2026-46538 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32677.
When was CVE-2026-46538 published?
CVE-2026-46538 was published on 2026-05-27 and last updated on 2026-06-17.

References

Other CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities

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