{"id":"CVE-2026-49446","state":"PUBLISHED","title":"Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server","description":"Cosmos provides users the ability self-host a home server by acting as a secure gateway to your application, as well as a server manager. Prior to 0.22.19, tokenMiddleware in src/proxy/routerGen.go can return through the Constellation tunnel bypass before removing x-cosmos-user, x-cosmos-role, x-cosmos-user-role, and x-cosmos-mfa headers and before invoking AdminOnlyWithRedirect. An attacker with a valid x-cstln-auth API key for an enrolled device who reaches Cosmos through the Constellation Nebula tunnel can supply a chosen x-cosmos-user value to a route with AuthEnabled enabled when the upstream application trusts that forward-auth header. The request can bypass Cosmos JWT, password, MFA, and AdminOnly checks, allowing user impersonation and admin-tier reads or writes exposed by the proxied application. This issue is fixed in version 0.22.19.","publishedAt":"2026-09-15T14:31:24.778Z","updatedAt":"2026-09-15T14:50:54.216Z","severity":{"score":6.1,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["azukaar Cosmos-Server"],"affected":[{"vendor":"azukaar","product":"Cosmos-Server","versions":[{"version":"< 0.22.19","status":"affected"}]}],"references":["https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659","https://github.com/azukaar/Cosmos-Server/commit/59c561d686c8f9843b3e092b50f6346c481d8bbf","https://github.com/azukaar/Cosmos-Server/releases/tag/v0.22.19"],"weaknesses":["CWE-285","CWE-290"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/49xxx/CVE-2026-49446.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-49446","state":"PUBLISHED","datePublished":"2026-09-15T14:31:24.778Z","dateUpdated":"2026-09-15T14:50:54.216Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-30T02:43:33.106Z"},"containers":{"cna":{"title":"Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server","descriptions":[{"lang":"en","value":"Cosmos provides users the ability self-host a home server by acting as a secure gateway to your application, as well as a server manager. Prior to 0.22.19, tokenMiddleware in src/proxy/routerGen.go can return through the Constellation tunnel bypass before removing x-cosmos-user, x-cosmos-role, x-cosmos-user-role, and x-cosmos-mfa headers and before invoking AdminOnlyWithRedirect. An attacker with a valid x-cstln-auth API key for an enrolled device who reaches Cosmos through the Constellation Nebula tunnel can supply a chosen x-cosmos-user value to a route with AuthEnabled enabled when the upstream application trusts that forward-auth header. The request can bypass Cosmos JWT, password, MFA, and AdminOnly checks, allowing user impersonation and admin-tier reads or writes exposed by the proxied application. This issue is fixed in version 0.22.19."}],"affected":[{"vendor":"azukaar","product":"Cosmos-Server","versions":[{"version":"< 0.22.19","status":"affected"}]}],"references":[{"url":"https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659","name":"https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/azukaar/Cosmos-Server/commit/59c561d686c8f9843b3e092b50f6346c481d8bbf","name":"https://github.com/azukaar/Cosmos-Server/commit/59c561d686c8f9843b3e092b50f6346c481d8bbf","tags":["x_refsource_MISC"]},{"url":"https://github.com/azukaar/Cosmos-Server/releases/tag/v0.22.19","name":"https://github.com/azukaar/Cosmos-Server/releases/tag/v0.22.19","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"ADJACENT_NETWORK","availabilityImpact":"NONE","baseScore":6.1,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"HIGH","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-285","lang":"en","description":"CWE-285: Improper Authorization","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-290","lang":"en","description":"CWE-290: Authentication Bypass by Spoofing","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-15T14:31:24.778Z"},"source":{"advisory":"GHSA-2rx5-2g7j-2659","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-15T14:50:32.130417Z","id":"CVE-2026-49446","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-15T14:50:54.216Z"}}]}}}