{"affected":[{"package":{"ecosystem":"Hex","name":"ash_authentication_oauth2_server","purl":"pkg:hex/ash_authentication_oauth2_server"},"ranges":[{"events":[{"introduced":"0.1.0"},{"fixed":"0.3.1"}],"type":"SEMVER"}],"versions":["0.1.0","0.1.1","0.1.2","0.1.3","0.2.0","0.2.1","0.2.2","0.3.0"]},{"ranges":[{"events":[{"introduced":"855b578037c5ded18e8a6e60f42e56bde4905fae"},{"fixed":"30a87101871775d27d79f9ad6f29eafa4779e118"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server","type":"GIT"}]}],"aliases":["GHSA-fxc6-vp68-87pw","CVE-2026-82758"],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Peter Ullrich","type":"REPORTER"},{"name":"Zach Daniel / Ash Project","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-115"],"cpe_ids":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-287"]},"details":"## Summary\n\nImproper Authentication vulnerability in ash-project ash\\_authentication\\_oauth2\\_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.\n\nresolve\\_secret/3 in AshAuthentication.Oauth2Server (reached through \\_\\_resolve\\_secret\\_\\_!) treated any return other than {:ok, \\_} or :error from a configured {module, function, args} or 2-arity-function secret provider as a valid secret, wrapping nil, false, or \"\" as {:ok, value}. When the initial\\_access\\_token resolves to such an empty value, POST /oauth/register compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as signing\\_secret.\n\nThis issue affects ash\\_authentication\\_oauth2\\_server: from 0.1.0 before 0.3.1.\n\n## Configuration\n\nReachable only when the server configures an initial\\_access\\_token (so Dynamic Client Registration is meant to require one) and the configured secret provider returns an empty value (nil, false, or \"\") or an {:error, \\_} for it, rather than a non-empty binary.","id":"EEF-CVE-2026-82758","modified":"2026-09-07T22:32:18.190096Z","published":"2026-09-07T22:32:17.027Z","references":[{"type":"ADVISORY","url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-fxc6-vp68-87pw"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-82758.html"},{"type":"FIX","url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/30a87101871775d27d79f9ad6f29eafa4779e118"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash_authentication_oauth2_server"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint","upstream":[]}