CVE-2026-77775Headroom Proxy Sends Upstream Requests to a Client-Supplied Base URL Without Address Validation
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 8.6 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
- Weakness (CWE)
- CWE-918
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Aug 21, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Headroom Labs Headroom headroom_labs:headroom (from the name) | before 0.36.1; 0.36.1 not affected | CNA record |
References
- https://github.com/headroomlabs-ai/headroom/pull/2207issue-tracking
- https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.pytechnical-description
- https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.pytechnical-description
- https://github.com/headroomlabs-ai/headroomproduct
- https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validationthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.