{"id":"CVE-2026-81637","aliases":["EEF-CVE-2026-81637","EUVD-2026-81481","GHSA-3vcj-gxx8-3p44"],"status":"published","title":"Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication","description":"Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.\n\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn \u003c- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","severity":{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00607,"percentile":0.49554,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-613"],"published":"2026-09-17T13:09:06Z","modified":"2026-10-28T02:30:56Z","fixes":[{"ecosystem":"Hex","package":"ash_authentication","fixed_in":["4.15.0","5.0.0-rc.14"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"ash_authentication","ranges":[{"type":"SEMVER","events":[{"introduced":"0.6.0"},{"fixed":"4.15.0"}]},{"type":"SEMVER","events":[{"introduced":"5.0.0-rc.0"},{"fixed":"5.0.0-rc.14"}]}],"versions":["3.0.3","3.1.0","3.10.0","3.10.1","3.10.2","3.10.3","3.10.4","3.10.5","3.10.6","3.10.7","3.10.8","3.11.0","3.11.1","3.11.10","3.11.11","3.11.12","3.11.13","3.11.14","3.11.15","3.11.16","3.11.2","3.11.3","3.11.4","3.11.5","3.11.6","3.11.7","3.11.8","3.11.9","3.12.0","3.12.1","3.12.2","3.12.3","3.12.4","3.2.0","3.2.1","3.2.2","3.3.0","3.3.1","3.5.0","3.5.1","3.5.2","3.5.3","3.6.0","3.6.1","3.7.0","3.7.1","3.7.2","3.7.3","3.7.4","3.7.5","3.7.6","3.7.8","3.7.9","3.8.0","3.9.0","3.9.1","3.9.2","3.9.3","3.9.4","3.9.5","3.9.6","4.0.0","4.0.0-rc.0","4.0.0-rc.1","4.0.0-rc.2","4.0.0-rc.3","4.0.0-rc.5","4.0.0-rc.6","4.0.1","4.0.2","4.0.3","4.0.4","4.1.0","4.10.0","4.11.0","4.12.0","4.13.0","4.13.1","4.13.2","4.13.3","4.13.4","4.13.5","4.13.6","4.13.7","4.14.0","4.14.1","4.14.2","4.2.0","4.2.1","4.2.2","4.2.3","4.2.4","4.2.5","4.2.6","4.2.7","4.3.0","4.3.1","4.3.10","4.3.11","4.3.12","4.3.2","4.3.3","4.3.4","4.3.5","4.3.6","4.3.7","4.3.8","4.3.9","4.4.0","4.4.1","4.4.2","4.4.3","4.4.4","4.4.5","4.4.6","4.4.7","4.4.8","4.4.9","4.5.0","4.5.1","4.5.2","4.5.3","4.5.4","4.5.5","4.5.6","4.6.0","4.6.1","4.6.2","4.6.3","4.6.4","4.7.0","4.7.1","4.7.2","4.7.3","4.7.4","4.7.5","4.7.6","4.8.0","4.8.1","4.8.2","4.8.3","4.8.5","4.8.6","4.8.7","4.9.0","4.9.1","4.9.2","4.9.3","4.9.4","4.9.5","4.9.6","4.9.7","4.9.8","4.9.9","5.0.0-rc.0","5.0.0-rc.1","5.0.0-rc.10","5.0.0-rc.11","5.0.0-rc.12","5.0.0-rc.13","5.0.0-rc.2","5.0.0-rc.3","5.0.0-rc.4","5.0.0-rc.5","5.0.0-rc.6","5.0.0-rc.7","5.0.0-rc.8","5.0.0-rc.9"]}],"products":[{"vendor":"team-alembic","product":"ash_authentication"}],"references":[{"url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3vcj-gxx8-3p44","tags":["vendor-advisory","related","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-81637.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-81637","tags":["related","web"]},{"url":"https://github.com/team-alembic/ash_authentication/commit/c5f589058e04239263f50a1430eb17ea6d5dd1a2","tags":["related","fix","web"]},{"url":"https://github.com/team-alembic/ash_authentication/commit/bd4352303bc9d72d007f6818775267585a4bcc2f","tags":["patch","fix"]},{"url":"https://github.com/team-alembic/ash_authentication/commit/d7f939cd02bd618bcaa304631846fa75ffc419d7","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/2026/81xxx/CVE-2026-81637.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81637","tags":["advisory"]},{"url":"https://github.com/team-alembic/ash_authentication","tags":["package"]},{"url":"https://hex.pm/packages/ash_authentication","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-81637","title":"Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication","description":"Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.\n\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn \u003c- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","status":"published","published":"2026-09-17T13:09:06.571Z","modified":"2026-09-17T18:26:58.389Z","cvss":[{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low","assessor":"cna"}],"cwes":["CWE-613"],"updated_at":"2026-11-02T13:36:18.075535Z"}],"euvd":[{"id":"EUVD-2026-81481","description":"Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.\n\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn \u003c- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","status":"published","published":"2026-09-17T13:09:06Z","modified":"2026-09-17T18:26:58Z","cvss":[{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"}],"updated_at":"2026-11-02T17:28:10.833571Z"}],"nvd":[{"id":"CVE-2026-81637","description":"Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.\n\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn \u003c- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","status":"published","published":"2026-09-17T14:17:32.14Z","modified":"2026-09-18T18:16:18.527Z","cvss":[{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/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":"low","assessor":"secondary"}],"cwes":["CWE-613"],"updated_at":"2026-11-02T14:12:49.013904Z"}],"osv":[{"id":"CVE-2026-81637","title":"Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication","description":"Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.\n\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn \u003c- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","status":"published","published":"2026-09-17T13:09:06.571Z","modified":"2026-10-28T02:30:56.344276493Z","cvss":[{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"}],"cwes":["CWE-613"],"updated_at":"2026-11-02T15:45:18.131258Z"},{"id":"EEF-CVE-2026-81637","title":"Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication","description":"## Summary\n\nInsufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 `state` value to replay the callback and sign that victim into an attacker-controlled account.\n\n`AshAuthentication.Strategy.OAuth2.Plug.callback/2` clears the stored `session_params` through a rebinding step inside its `with` chain, `conn \u003c- delete_session(conn, session_key)`. Elixir evaluates the `else` block in the scope enclosing the `with`, so every failure path (the provider returning `?error=access_denied`, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches `store_authentication_result/2` holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.","status":"published","published":"2026-09-17T13:09:06.571Z","modified":"2026-09-17T13:26:03.786782668Z","cvss":[{"version":"4.0","score":2.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"}],"cwes":["CWE-613"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}