{"api_version":"1","generated_at":"2026-08-21T22:47:11+00:00","cve":"CVE-2026-77775","urls":{"html":"https://cve.report/CVE-2026-77775","api":"https://cve.report/api/cve/CVE-2026-77775.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-77775","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77775"},"summary":{"title":"Headroom Proxy Sends Upstream Requests to a Client-Supplied Base URL Without Address Validation","description":"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.","state":"PUBLISHED","assigner":"VulnCheck","published_at":"2026-08-21 12:16:36","updated_at":"2026-08-21 12:16:36"},"problem_types":["CWE-918","CWE-918 Server-Side Request Forgery (SSRF)"],"metrics":[{"version":"4.0","source":"disclosure@vulncheck.com","type":"Secondary","score":"7.7","severity":"HIGH","vector":"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","data":{"version":"4.0","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","baseScore":7.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}},{"version":"4.0","source":"CNA","type":"CVSS","score":"7.7","severity":"HIGH","vector":"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","data":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":7.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"NONE","userInteraction":"NONE","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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"}},{"version":"3.1","source":"disclosure@vulncheck.com","type":"Primary","score":"8.6","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","baseScore":8.6,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"8.6","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.6,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","version":"3.1"}}],"references":[{"url":"https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py","name":"https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py","refsource":"disclosure@vulncheck.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/headroomlabs-ai/headroom","name":"https://github.com/headroomlabs-ai/headroom","refsource":"disclosure@vulncheck.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py","name":"https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py","refsource":"disclosure@vulncheck.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation","name":"https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation","refsource":"disclosure@vulncheck.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/headroomlabs-ai/headroom/pull/2207","name":"https://github.com/headroomlabs-ai/headroom/pull/2207","refsource":"disclosure@vulncheck.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-77775","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77775","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Headroom Labs","product":"Headroom","version":"affected 0.36.1 semver","platforms":[]},{"source":"CNA","vendor":"Headroom Labs","product":"Headroom","version":"unaffected 0.36.1 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Gregory Tan (Grg0rry)","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-77775","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-08-21T11:39:38.994271Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-08-21T11:44:34.968Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"collectionURL":"https://pypi.org","defaultStatus":"unaffected","packageName":"headroom-ai","packageURL":"pkg:pypi/headroom-ai","product":"Headroom","programFiles":["headroom/proxy/handlers/openai.py","headroom/providers/proxy_routes.py"],"repo":"https://github.com/headroomlabs-ai/headroom","vendor":"Headroom Labs","versions":[{"lessThan":"0.36.1","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"0.36.1","versionType":"semver"}]}],"credits":[{"lang":"en","type":"finder","value":"Gregory Tan (Grg0rry)"}],"datePublic":"2026-08-20T00:00:00.000Z","descriptions":[{"lang":"en","value":"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."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.6,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","version":"3.1"},"format":"CVSS"},{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":7.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"NONE","userInteraction":"NONE","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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","description":"Server-Side Request Forgery (SSRF)","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-21T11:22:51.107Z","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck"},"references":[{"name":"Pull Request #2207 addressing the assessment findings","tags":["issue-tracking"],"url":"https://github.com/headroomlabs-ai/headroom/pull/2207"},{"name":"Header handling in the OpenAI proxy handler at v0.29.0","tags":["technical-description"],"url":"https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py"},{"name":"is_safe_upstream_url guard introduced by the fix","tags":["technical-description"],"url":"https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/upstream_guard.py"},{"tags":["product"],"url":"https://github.com/headroomlabs-ai/headroom"},{"name":"VulnCheck Advisory: Headroom Proxy Sends Upstream Requests to a Client-Supplied Base URL Without Address Validation","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/headroom-proxy-sends-upstream-requests-to-a-client-supplied-base-url-without-address-validation"}],"title":"Headroom Proxy Sends Upstream Requests to a Client-Supplied Base URL Without Address Validation"}},"cveMetadata":{"assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","assignerShortName":"VulnCheck","cveId":"CVE-2026-77775","datePublished":"2026-08-21T11:22:51.107Z","dateReserved":"2026-08-21T11:09:25.553Z","dateUpdated":"2026-08-21T11:44:34.968Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-21 12:16:36","lastModifiedDate":"2026-08-21 12:16:36","problem_types":["CWE-918","CWE-918 Server-Side Request Forgery (SSRF)"],"metrics":{"cvssMetricV40":[{"source":"disclosure@vulncheck.com","type":"Secondary","cvssData":{"version":"4.0","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","baseScore":7.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"disclosure@vulncheck.com","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","baseScore":8.6,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":4}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-21T11:39:38.994271Z","id":"CVE-2026-77775","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"77775","Ordinal":"1","Title":"Headroom Proxy Sends Upstream Requests to a Client-Supplied Base","CVE":"CVE-2026-77775","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"77775","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"Headroom Proxy Sends Upstream Requests to a Client-Supplied Base"}]}}}