CVE-2026-87011: Openwebui Open Webui

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.0 until 0.11.1, the unauthenticated POST /oauth/backchannel-logout handler in backend/open_webui/utils/oauth.py fetched the OIDC discovery document and signing keys before validating a submitted logout token. Each request repeated uncached network fetches, and the signing-key lookup blocked the async event loop, so requests carrying invalid tokens could stall the single-worker instance and amplify traffic to the identity provider when ENABLE_OAUTH_BACKCHANNEL_LOGOUT was enabled. This issue is fixed in version 0.11.1.

Affected products

• Openwebui Open Webui: from 0.9.0, before 0.11.1 (fixed in 0.11.1)

Published 2026-09-09. Last modified 2026-09-15.