Headroom Proxy Treats the Client-Supplied x-headroom-user-id Header as an Authenticated Identity (CVE-2026-77776) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-77776

Headroom Proxy Treats the Client-Supplied x-headroom-user-id Header as an Authenticated Identity

Answer in brief

CVE-2026-77776 records a Unknown severity vulnerability in Headroom Proxy Treats the Client-Supplied x-headroom-user-id Header as an Authenticated Identity. The current sources do not mark it as known exploited. The current feed maps Headroom Labs/Headroom (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 21, 2026Updated Aug 21, 2026Source checked Aug 21, 2026First seen by HOL Aug 21, 2026Material review Aug 21, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Headroom Labs/Headroom (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Headroom Labs/Headroomgeneric	>=0 <0.36.1	0.36.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for Headroom Labs/Headroom.
Review the reported fix. Update Headroom Labs/Headroom to 0.36.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 21, 2026

Sources and claim methodology

Upstream source description

Headroom's LLM proxy derives the memory owner from the x-headroom-user-id request header. The header is read directly at several points in headroom/proxy/handlers/openai.py, including the chat completion and websocket paths, and nothing binds the value to the caller. A client can therefore name another user's identifier and read or write that user's stored LLM memory. The fix introduces a single resolve_memory_identity seam in headroom/proxy/identity.py that honors the header only for loopback or allowlisted callers and otherwise binds the identity to the proxy-token fingerprint or the operating system user. 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.

Quoted source text, attributed separately from HOL analysis.