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Vulnerabilities/CVE-2026-77775Public Intelligence Dossier
Source: Source type: NVD · Limited verification•Last verified: •Collection Degraded
CVE-2026-77775Unknown / EvaluatingHIGH (raw)CVSS 8.6CWE-918

Headroom's LLM proxy lets a client choose the upstream destination with the x-headroom-base-url request header

Published: 21 Aug 2026•Last updated: 16 Oct 2026, 12:40 AM IST•Source identifier: disclosure@vulncheck.com
Dossier completeness: source-provided sections 1 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
8.6HIGH (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Metric sourcedisclosure@vulncheck.com
EPSS probability
0.6%0.006
Percentile47th
Weakness type
CWE-918
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

0 source-backed products
Affected products and versions (source)Not provided by source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched ssrf (CWE-918); network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify affected server-side request features and deployed versions.Telemetry: Application inventory · The specific feature must be confirmed from the advisory. · Rule ssrf
  2. Identify devices reporting this CVE and note which expose the affected service to untrusted networks.Telemetry: DeviceTvmSoftwareVulnerabilities · A network-reachable, no-privilege vector makes internet-facing instances the first exposure question. · Rule network-unauthenticated

Exploitation evidence

  1. Review unusual outbound connections from the affected service to internal or metadata endpoints.Telemetry: DeviceNetworkEvents · Outbound patterns can support SSRF hunting. · Rule ssrf
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Exploitation evidence

  1. Review inbound connections to the affected service from unexpected sources since the advisory date.Telemetry: DeviceNetworkEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule network-unauthenticated

Response

  1. Verify the vendor fix and confirm expected egress after deployment.Telemetry: DeviceNetworkEvents · Post-change telemetry helps validate mitigation. · Rule ssrf

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
disclosure@vulncheck.com
Record status · verification
UPDATED · NVD API
CPE
Unknown
Detection Hunting Query

— No published hunting query names this record. Browse community and library queries instead.

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Correlated briefings

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.