GitLab AI Gateway Auth Bypass via Host Header Override (18.10-19.2.2)
CVE-2026-75871 Published on August 27, 2026
Server-Side Request Forgery (SSRF) in GitLab AI Gateway
GitLab has remediated a vulnerability in the GitLab AI Gateway component affecting all versions of the AI Gateway from 18.10 to 19.0.12, 19.1 to 19.1.7, and 19.2 to 19.2.2 that could have allowed an authenticated user with Duo Agent Platform access to redirect outbound model requests to an externally-controlled endpoint via a crafted inline flow configuration that overrides the HTTP Host header, resulting in disclosure of Google Cloud Vertex cloud service credentials and private signing keys.
Vulnerability Analysis
CVE-2026-75871 can be exploited with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-75871. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a SSRF Vulnerability?
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
CVE-2026-75871 has been classified to as a SSRF vulnerability or weakness.
Products Associated with CVE-2026-75871
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Affected Versions
GitLab AI Gateway:- Version 18.10 and below 19.0.12 is affected.
- Version 19.1 and below 19.1.7 is affected.
- Version 19.2 and below 19.2.2 is affected.