Microsoft UFO: Authenticated task-result request can deadlock UFO server session manager

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Microsoft UFO is an open-source framework for intelligent automation across devices and platforms. Prior to 3.0.9, the /api/task_result/{task_name} endpoint calls SessionManager.get_result_by_task() in ufo/server/services/session_manager.py, which acquires a non-reentrant lock and then calls SessionManager.get_result() to acquire the same lock again when the task name maps to a session. An authenticated caller who knows or creates a mapped task name can therefore block the request indefinitely, and in the default single-process server configuration the blocked event-loop thread prevents other HTTP, WebSocket, and dependent background interactions. Unknown task names do not reach the nested call and are not affected. This issue is fixed in version 3.0.9.

Source published

6 Oct 2026 14:10:52 UTC

Source modified

6 Oct 2026 17:41:54 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H