CVE-2026-45339
Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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. This vulnerability is fixed in 0.9.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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. This vulnerability is fixed in 0.9.0.
- Record
CVE-2026-45339- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-863
- Updated
- 2026-11-02
EUVDEUVD-2026-30612
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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. This vulnerability is fixed in 0.9.0.
- Record
EUVD-2026-30612- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-57q6-fvp4-pqmm
Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
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.
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
- Record
GHSA-57q6-fvp4-pqmm- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-863
- Updated
- 2026-11-03
NVD
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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. This vulnerability is fixed in 0.9.0.
- Record
CVE-2026-45339- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-863
- Updated
- 2026-11-02
OSV
Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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. This vulnerability is fixed in 0.9.0.
- Record
CVE-2026-45339- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-863
- Updated
- 2026-11-02
OSVGHSA-57q6-fvp4-pqmm
Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
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.
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
- Record
GHSA-57q6-fvp4-pqmm- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-863
- Updated
- 2026-11-03
OSVPYSEC-2026-3543
Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
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.
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
- Record
PYSEC-2026-3543- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
open-webuiPyPI |
before 0.9.0 | 0.9.0 |
open-webuiPyPI |
before 0.9.0, plus listed versions 0.1.1240.1.1250.2.00.2.10.2.2 Show 45 moreShow less0.2.30.2.40.2.50.3.00.3.10.3.100.3.120.3.130.3.140.3.150.3.160.3.170.3.17.dev20.3.17.dev30.3.17.dev40.3.17.dev50.3.180.3.190.3.20.3.200.3.210.3.220.3.230.3.240.3.250.3.260.3.270.3.27.dev10.3.27.dev20.3.27.dev30.3.280.3.290.3.30.3.300.3.30.dev10.3.30.dev20.3.310.3.31.dev10.3.320.3.330.3.33.dev10.3.340.3.350.3.40.3.5 |
0.9.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts, references | GitHub Advisories, OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-45339 is a medium vulnerability (CVSS 6.5) in Openwebui Open Webui, published May 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 23rd percentile. Fixed in open-webui 0.9.0.
References
github.com/open-webui/open-webui/security/advisories/GHSA-57q6-fvp4-pqmm
nvd.nist.gov/vuln/detail/CVE-2026-45339
pypi.org/project/open-webui
Left out here: 101 versions. The JSON record has them.