Medium, CVSS 6.5PyPIAmendedPublished
Open WebUI's API key endpoint restrictions bypassed via x-api-key header — full message processing on restricted endpoints
CVE-2026-45339 · GHSA-57q6-fvp4-pqmm
- Affected
- PyPI open-webu <= 0.8.12
- Fixed in
- 0.9.0· Vendor fix available
- Issue
- Open WebUI allows admins to restrict which API endpoints an API key can access. When an API key is restricted from `/api/v1/messages`, requests using the `Authorization: Bearer sk-...` header are correctly blocked with 403. However, the same key sent via the `x-api-key` header bypasses the restriction entirely — the request is authenticated, the model is invoked, and a full response is returned. Details Open WebUI's Anthropic-compatible API path accepts authentication via `x-api-key` header (standard for the Anthropic API). The endpoint restriction check only applies to keys presented via the `Authorization` header. When the same `sk-...` key is supplied in `x-api-key`, the restriction check is skipped but the key is still valid for authentication. This means any API key, regardless of its configured endpoint restrictions, can access any API endpoint by simply using `x-api-key` instead of `Authorization`. PoC Verified against Open WebUI v0.8.11. Setup:…
Recommended action: Upgrade to 0.9.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.