PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-46538 microsoft CVE debrief

Microsoft UFO is an open-source framework for intelligent automation across devices and platforms. In version 3.0.1-4-ge2626659, the constellation client tracks pending task responses by session_id only and does not verify that a TASK_END message originated 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. While the pending task record stores the expected device ID, the completion path ignores this binding. An authenticated peer device can send a forged TASK_END message with the same session_id, causing the constellation to accept the response and complete the victim device's pending Future with attacker-controlled result data. This constitutes an authenticated cross-device task-result injection vulnerability.

Vendor
microsoft
Product
UFO
CVSS
MEDIUM 5.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-05-28
Advisory published
2026-05-27
Advisory updated
2026-05-28

Who should care

Organizations deploying Microsoft UFO for cross-device automation, particularly those with multi-tenant or multi-user device environments where peer devices may have different trust levels or compromise boundaries.

Technical summary

The vulnerability exists in the constellation client's task completion handling. When a task is dispatched to a target device, the client creates a pending Future indexed by session_id. The stored pending record includes the expected device ID, but the completion handler does not validate that the incoming TASK_END message's device ID matches this expectation. An attacker with valid credentials on a peer device can intercept or predict session_id values and submit forged TASK_END messages. The constellation client will match the session_id, complete the Future, and propagate attacker-controlled data as the task result. This breaks the integrity guarantee of task execution without requiring compromise of the target device.

Defensive priority

MEDIUM

Recommended defensive actions

  • Review Microsoft UFO GitHub Security Advisory GHSA-wmq2-74rj-7pjc for detailed technical information and remediation guidance
  • Upgrade Microsoft UFO to a version containing the security fix for CVE-2026-46538
  • Audit constellation client implementations for custom modifications that may replicate the vulnerable session_id-only tracking pattern
  • Implement additional verification in task completion handlers to validate that TASK_END messages originate from the expected device ID
  • Monitor for anomalous task completion patterns that may indicate exploitation attempts
  • Review access controls to limit which authenticated devices can communicate with the constellation client

Evidence notes

The vulnerability was disclosed via GitHub Security Advisory GHSA-wmq2-74rj-7pjc and subsequently published in the NVD. The CVSS 3.1 vector (AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L) indicates network attack vector with high attack complexity, low privileges required, no user interaction, and high impact to integrity with low availability impact. CWE-294 (Authentication Bypass by Capture-replay) and CWE-345 (Insufficient Verification of Data Authenticity) are identified as relevant weakness classifications.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46538 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46538

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46538 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46538

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.