Vulnerability-Lookup

CVE-2026-77775 (GCVE-0-2026-77775)

Vulnerability from cvelistv5 – Published: 2026-08-21 11:22 – Updated: 2026-08-21 11:44

Title

Headroom Proxy Sends Upstream Requests to a Client-Supplied Base URL Without Address Validation

Summary

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.

Severity

8.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

7.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 11:39 UTC

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

VulnCheck mitre root

References

5 references

URL	Tags
https://github.com/headroomlabs-ai/headroom/pull/2207	issue-tracking
https://github.com/headroomlabs-ai/headroom/blob/…	technical-description
https://github.com/headroomlabs-ai/headroom/blob/…	technical-description
https://github.com/headroomlabs-ai/headroom	product
https://www.vulncheck.com/advisories/headroom-pro…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
Headroom Labs	Headroom	Affected: 0 , < 0.36.1 (semver) Unaffected: 0.36.1 (semver)	guessed

Date Public

2026-08-20 00:00

Credits

Gregory Tan (Grg0rry)

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-77775

Vulnerability from fkie_nvd - Published: 2026-08-21 12:16 - Updated: 2026-08-21 12:16

Severity

8.6 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Summary

References

	URL	Tags
	disclosure@vulncheck.com	https://github.com/headroomlabs-ai/headroom
	disclosure@vulncheck.com	https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py
	disclosure@vulncheck.com	https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py
	disclosure@vulncheck.com	https://github.com/headroomlabs-ai/headroom/pull/2207
	disclosure@vulncheck.com	https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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    }
  ],
  "id": "CVE-2026-77775",
  "lastModified": "2026-08-21T12:16:36.813",
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          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77775",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-21T11:39:38.994271Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-21T12:16:36.813",
  "references": [
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/headroomlabs-ai/headroom"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/headroomlabs-ai/headroom/pull/2207"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation"
    }
  ],
  "sourceIdentifier": "disclosure@vulncheck.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-918"
        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Primary"
    }
  ]
}

GHSA-4J5R-9P93-J2PX

Vulnerability from github – Published: 2026-08-21 12:30 – Updated: 2026-08-21 12:30

Details

Severity

8.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

7.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-77775"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-21T12:16:36Z",
    "severity": "HIGH"
  },
  "details": "Headroom\u0027s 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.",
  "id": "GHSA-4j5r-9p93-j2px",
  "modified": "2026-08-21T12:30:34Z",
  "published": "2026-08-21T12:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77775"
    },
    {
      "type": "WEB",
      "url": "https://github.com/headroomlabs-ai/headroom/pull/2207"
    },
    {
      "type": "WEB",
      "url": "https://github.com/headroomlabs-ai/headroom"
    },
    {
      "type": "WEB",
      "url": "https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py"
    },
    {
      "type": "WEB",
      "url": "https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-77775 (GCVE-0-2026-77775)

FKIE_CVE-2026-77775

GHSA-4J5R-9P93-J2PX

Tags

Sightings

Nomenclature