Headroom Labs up to 0.36.0 LLM Proxy openai.py x-headroom-base-url improper authorization

Summaryinfo

A vulnerability was found in Headroom Labs Headroom up to 0.36.0. It has been declared as problematic. The affected element is the function _resolve_openai_upstream_base/_select_passthrough_base_url of the file headroom/proxy/handlers/openai.py of the component LLM Proxy. The manipulation of the argument x-headroom-base-url results in improper authorization. This vulnerability is reported as CVE-2026-77775. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as problematic has been found in Headroom Labs Headroom up to 0.36.0. Affected is the function _resolve_openai_upstream_base/_select_passthrough_base_url of the file headroom/proxy/handlers/openai.py of the component LLM Proxy. The manipulation of the argument x-headroom-base-url with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality. CVE summarizes:

Headroom's LLM proxy lets a client choose the upstream destination with the x-headroom-base-url request header. _resolve_openai_upstream_base in headroom/proxy/handlers/openai.py accepts the header value, requires only that it parse with an http or https scheme and a hostname, and returns it for use as the upstream base; _select_passthrough_base_url in headroom/providers/proxy_routes.py reads the same header for the passthrough routes. No check rejects loopback, link-local, or RFC 1918 destinations, and because the component is a proxy the upstream response is returned to the caller, so the request reaches internal services and cloud metadata addresses and their responses are disclosed. The Authorization header accompanying the request is forwarded unchanged to the caller-designated host. The pip console script binds 127.0.0.1 by default, but the reference docker-compose.yml ships --host 0.0.0.0 with published ports and no required HEADROOM_PROXY_TOKEN, which the server itself warns about at startup, so a deployment following the shipped compose exposes the affected data-plane routes to the network without authentication.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-77775 since 08/21/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1548.002.

Upgrading to version 0.36.1 eliminates this vulnerability.

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Productinfo

Vendor

• Headroom Labs

Name

• Headroom

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31
• 0.32
• 0.33
• 0.34
• 0.35
• 0.36.0

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CPE 2.2info

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