{"id":"GHSA-xg6x-h9c9-2m83","summary":"Better Auth Has Two-Factor Authentication Bypass via Premature Session Caching (session.cookieCache)","details":"### Summary\n\nUnder certain configurations, sessions may be considered valid before two-factor authentication (2FA) is fully completed. This can allow access to authenticated routes without verifying the second factor.\n\n---\n\n### Description\n\nWhen two-factor authentication is enabled, the authentication flow correctly identifies users who require additional verification and defers full authentication until the second factor is completed.\n\nHowever, when `session.cookieCache` is enabled, the session generated during the initial sign-in step may be cached as valid **prior to 2FA verification**. Subsequent session lookups may then return this cached session without re-evaluating the 2FA requirement.\n\nThis results in a situation where session validity can be established before all authentication constraints are satisfied.\n\n---\n\n### Impact\n\nAn attacker (or user) with valid primary credentials may gain access to protected application routes without completing the required second authentication factor.\n\nAny application using `better-auth` with both two-factor authentication and session cookie caching enabled may be affected.\n\n---\n\n### Mitigation\n\n* Upgrade to a version of `better-auth` that includes the fix for this issue.\n* Ensure that session caching does not treat sessions as fully authenticated until all required authentication steps, including 2FA, are completed.\n* As a temporary workaround, disable `session.cookieCache` when using two-factor authentication.","aliases":["CVE-2026-67337"],"modified":"2026-08-02T03:56:49.020545992Z","published":"2026-04-03T03:29:59Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-288"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-04-03T03:29:59Z"},"references":[{"type":"WEB","url":"https://github.com/better-auth/better-auth/security/advisories/GHSA-xg6x-h9c9-2m83"},{"type":"PACKAGE","url":"https://github.com/better-auth/better-auth"}],"affected":[{"package":{"name":"better-auth","ecosystem":"npm","purl":"pkg:npm/better-auth"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.9"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-xg6x-h9c9-2m83/GHSA-xg6x-h9c9-2m83.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"}]}