{"id":"CVE-2026-81637","title":"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\nAshAuthenticat…","summary":"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\nAshAuthenticat…","severity":"low","cvss":2.3,"cvssVector":"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","cwe":["CWE-613"],"vendor":"team-alembic","product":"ash_authentication","affected":["ash_authentication >= 0.6.0 < 4.15.0","ash_authentication >= 5.0.0-rc.0 < 5.0.0-rc.14","team-alembic/ash_authentication >= c5f589058e04239263f50a1430eb17ea6d5dd1a2 < *"],"published":"2026-09-17","updated":"2026-09-18","sourceUpdated":"2026-09-18T18:16:18.527","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81637","references":[{"url":"https://cna.erlef.org/cves/CVE-2026-81637.html","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/team-alembic/ash_authentication/commit/bd4352303bc9d72d007f6818775267585a4bcc2f","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/team-alembic/ash_authentication/commit/c5f589058e04239263f50a1430eb17ea6d5dd1a2","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/team-alembic/ash_authentication/commit/d7f939cd02bd618bcaa304631846fa75ffc419d7","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3vcj-gxx8-3p44","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-81637","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}],"tags":["nvd","cve.org"],"epss":0.0048,"epssPercentile":0.40414,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-17T18:26:48.969731Z"},"cvssSource":"cna","ingestedAt":"2026-09-17T13:18:16.985Z","slug":"CVE-2026-81637","body":"## Overview\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\nAshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn <- 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":13,"depthScoreParts":{"impact":12.6,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}