{"cve":"CVE-2026-81637","nvd":{"published":"2026-09-17T14:17:32.140","modified":"2026-09-18T18:16:18.527","status":"Deferred","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 <- 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.","cvss_v4":{"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","score":2.3},"cvss_v3":null,"cwes":["CWE-613"],"references":["https://cna.erlef.org/cves/CVE-2026-81637.html","https://github.com/team-alembic/ash_authentication/commit/bd4352303bc9d72d007f6818775267585a4bcc2f","https://github.com/team-alembic/ash_authentication/commit/c5f589058e04239263f50a1430eb17ea6d5dd1a2","https://github.com/team-alembic/ash_authentication/commit/d7f939cd02bd618bcaa304631846fa75ffc419d7","https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3vcj-gxx8-3p44"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-81637","score":0.00607,"percentile":0.49056,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}