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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-87011
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-09 21:17:05 UTC
Updated2026-09-10 14:50:07 UTC
DescriptionOpen 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003390000 probability, percentile 0.269290000 (date 2026-09-10)

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Open-webui Open-webui affected >= 0.9.0, < 0.11.1 Not specified

References

ReferenceSourceLinkTags
github.com/open-webui/open-webui/commit/aeda6ff13a25d3b3ba1b303609f35382... [email protected] github.com
github.com/open-webui/open-webui/security/advisories/GHSA-3g9q-v48f-hh9w [email protected] github.com
github.com/open-webui/open-webui/releases/tag/v0.11.1 [email protected] github.com
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