{"id":"CVE-2026-82757","state":"PUBLISHED","title":"ash_authentication_oauth2_server CIMD fetcher classifies IPv4-in-IPv6 and site-local addresses as public, allowing SSRF","description":"Server-Side Request Forgery (SSRF) vulnerability in ash-project ash_authentication_oauth2_server allows an attacker who controls a client metadata URL and its DNS to make the server connect to internal or loopback addresses.\n\npublic_ip?/1 in AshAuthentication.Oauth2Server.CIMD.ReqFetcher enforces the outbound policy for CIMD metadata fetches. It classified several address forms as publicly routable that are not: IPv4-compatible ::/96 (for example ::127.0.0.1), SIIT IPv4-translated ::ffff:0:0:0/96, and deprecated site-local fec0::/10. A returned AAAA record in one of these ranges passed the policy, so a fetch pinned to that address reached space the policy was meant to block.\n\nThis issue affects ash_authentication_oauth2_server: from 0.3.0 before 0.3.1.","publishedAt":"2026-09-07T22:31:34.656Z","updatedAt":"2026-09-08T14:43:57.511Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["ash-project ash_authentication_oauth2_server"],"affected":[{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash_authentication_oauth2_server","packageURL":"pkg:hex/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"0.3.0","status":"affected","lessThan":"0.3.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher'"],"programFiles":["lib/ash_authentication/oauth2_server/cimd/req_fetcher.ex"],"programRoutines":[{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':public_ip?/1"},{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':fetch/2"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server"},{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash-project/ash_authentication_oauth2_server","packageURL":"pkg:github/ash-project/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"e713a9ba816761140c226e2ca55b75c0b93f5984","status":"affected","lessThan":"268b591261a3473ab9b87272963e4dd2fd99d972","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher'"],"programFiles":["lib/ash_authentication/oauth2_server/cimd/req_fetcher.ex"],"programRoutines":[{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':public_ip?/1"},{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':fetch/2"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server"}],"references":["https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv","https://cna.erlef.org/cves/CVE-2026-82757.html","https://osv.dev/vulnerability/EEF-CVE-2026-82757","https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/82xxx/CVE-2026-82757.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-82757","state":"PUBLISHED","datePublished":"2026-09-07T22:31:34.656Z","dateUpdated":"2026-09-08T14:43:57.511Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-08-31T01:00:10.817Z"},"containers":{"cna":{"title":"ash_authentication_oauth2_server CIMD fetcher classifies IPv4-in-IPv6 and site-local addresses as public, allowing SSRF","descriptions":[{"lang":"en","value":"Server-Side Request Forgery (SSRF) vulnerability in ash-project ash_authentication_oauth2_server allows an attacker who controls a client metadata URL and its DNS to make the server connect to internal or loopback addresses.\n\npublic_ip?/1 in AshAuthentication.Oauth2Server.CIMD.ReqFetcher enforces the outbound policy for CIMD metadata fetches. It classified several address forms as publicly routable that are not: IPv4-compatible ::/96 (for example ::127.0.0.1), SIIT IPv4-translated ::ffff:0:0:0/96, and deprecated site-local fec0::/10. A returned AAAA record in one of these ranges passed the policy, so a fetch pinned to that address reached space the policy was meant to block.\n\nThis issue affects ash_authentication_oauth2_server: from 0.3.0 before 0.3.1."}],"affected":[{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash_authentication_oauth2_server","packageURL":"pkg:hex/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"0.3.0","status":"affected","lessThan":"0.3.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher'"],"programFiles":["lib/ash_authentication/oauth2_server/cimd/req_fetcher.ex"],"programRoutines":[{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':public_ip?/1"},{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':fetch/2"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server"},{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash-project/ash_authentication_oauth2_server","packageURL":"pkg:github/ash-project/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"e713a9ba816761140c226e2ca55b75c0b93f5984","status":"affected","lessThan":"268b591261a3473ab9b87272963e4dd2fd99d972","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher'"],"programFiles":["lib/ash_authentication/oauth2_server/cimd/req_fetcher.ex"],"programRoutines":[{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':public_ip?/1"},{"name":"'Elixir.AshAuthentication.Oauth2Server.CIMD.ReqFetcher':fetch/2"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server"}],"references":[{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wprp-8gvj-p6cv","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-82757.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82757","tags":["related"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/268b591261a3473ab9b87272963e4dd2fd99d972","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","description":"CWE-918 Server-Side Request Forgery (SSRF)","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-09-07T22:31:34.656Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Reachable only when Client ID Metadata Documents are enabled (<code>cimd_enabled?: true</code>), so the authorize endpoint fetches attacker-suppliable metadata URLs, and an internal or loopback target resolves to one of the affected IPv6 address forms.</p>"},{"base64":false,"type":"text/markdown","value":"Reachable only when Client ID Metadata Documents are enabled (`cimd_enabled?: true`), so the authorize endpoint fetches attacker-suppliable metadata URLs, and an internal or loopback target resolves to one of the affected IPv6 address forms."}],"value":"Reachable only when Client ID Metadata Documents are enabled (cimd_enabled?: true), so the authorize endpoint fetches attacker-suppliable metadata URLs, and an internal or loopback target resolves to one of the affected IPv6 address forms."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*","versionEndExcluding":"0.3.1","versionStartIncluding":"0.3.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"reporter","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Zach Daniel / Ash Project"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-664","descriptions":[{"lang":"en","value":"CAPEC-664 Server Side Request Forgery"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-08T14:43:50.818031Z","id":"CVE-2026-82757","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-08T14:43:57.511Z"}}]}}}