CVE-2026-87011

Open WebUI: Unauthenticated requests can stall the server via uncached OIDC fetches in back-channel logout

State: Published
Severity: 7.5 High
Published: Sep 9, 2026
Updated: Sep 14, 2026
Reserved: Sep 8, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	GitHub_M

Weaknesses

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

Affected Products

Product	Versions
open-webuiopen-webui	>= 0.9.0, < 0.11.1Affected

References

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