Vulnerability · Published Sep 9, 2026 · Assigned by GitHub_M
CVE-2026-87011Open WebUI: Unauthenticated requests can stall the server via uncached OIDC fetches in back-channel logout
High 7.5
In plain English
A high-severity resource allocation without limits in open-webui from open-webui. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | open-webui | 0.11.1 | GHSA-3g9q-v48f-hh9w |
| PyPI | open-webui | 0.11.1 | PYSEC-2026-4117 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| open-webui | open-webui | >= 0.9.0, < 0.11.1 |
Weakness: CWE-405, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H