{"id":"CVE-2026-82758","aliases":["EEF-CVE-2026-82758","EUVD-2026-72540","GHSA-fxc6-vp68-87pw"],"status":"published","title":"ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint","description":"Improper 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.","severity":{"version":"4.0","score":6.3,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00686,"percentile":0.53138,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-287"],"published":"2026-09-07T22:32:17Z","modified":"2026-10-28T02:30:48Z","fixes":[{"ecosystem":"Hex","package":"ash_authentication_oauth2_server","fixed_in":["0.3.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"ash_authentication_oauth2_server","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"0.3.1"}]}],"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"]}],"products":[{"vendor":"ash-project","product":"ash_authentication_oauth2_server"}],"references":[{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-fxc6-vp68-87pw","tags":["vendor-advisory","related","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-82758.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82758","tags":["related","web"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/30a87101871775d27d79f9ad6f29eafa4779e118","tags":["patch","fix"]},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82758.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82758","tags":["advisory"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server","tags":["package"]},{"url":"https://hex.pm/packages/ash_authentication_oauth2_server","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-82758","title":"ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint","description":"Improper 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.","status":"published","published":"2026-09-07T22:32:17.027Z","modified":"2026-09-08T14:41:06.227Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T13:40:46.161838Z"}],"euvd":[{"id":"EUVD-2026-72540","description":"Improper 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.","status":"published","published":"2026-09-07T22:32:17Z","modified":"2026-09-08T14:41:06Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T17:28:29.426Z"}],"nvd":[{"id":"CVE-2026-82758","description":"Improper 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.","status":"published","published":"2026-09-07T23:16:53.123Z","modified":"2026-09-08T15:18:50.977Z","cvss":[{"version":"4.0","score":6.3,"vector":"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/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","level":"medium","assessor":"secondary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:12:44.436435Z"}],"osv":[{"id":"CVE-2026-82758","title":"ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint","description":"Improper 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.","status":"published","published":"2026-09-07T22:32:17.027Z","modified":"2026-10-28T02:30:48.12665122Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:45:18.482949Z"},{"id":"EEF-CVE-2026-82758","title":"ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint","description":"## 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\n`resolve_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## Configurations\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.","status":"published","published":"2026-09-07T22:32:17.027Z","modified":"2026-09-08T22:45:02.764947177Z","cvss":[{"version":"4.0","score":6.3,"vector":"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","level":"medium"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}