Medium severity · published May 15, 2026
CVE-2026-45339
Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OP
open-webui · open-webui
< 0.9.0 · source: vendor
OW
Open Webui · Openwebui
before 0.9.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45339
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45339
Exploit
https://github.com/open-webui/open-webui/security/advisories/GHSA-57q6-fvp4-pqmm
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