Resource exhaustion in Open-Webui
CVE-2026-87011
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (50.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- Open-Webui — versions >= 0.9.0, < 0.11.1
- Openwebui Open Webui
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-87011?
- CVE-2026-87011 is a high-severity vulnerability in Open-Webui, classified under Asymmetric Resource Consumption (Amplification). CVSS score: 7.5/10. Published 2026-09-09.
- How severe is CVE-2026-87011?
- High severity. CVSS v3 base score is 7.5 out of 10.