CVE-2026-87011

Summary

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 Software

VendorProductVersion RangeStatus
open-webuiopen-webui>= 0.9.0, < 0.11.1affected

Weaknesses

  • CWE-405: CWE-405: Asymmetric Resource Consumption (Amplification)
  • CWE-770: CWE-770: Allocation of Resources Without Limits or Throttling

References