{"id":"CVE-2026-67337","aliases":["GHSA-xg6x-h9c9-2m83"],"url":"https://o3.security/vulnerability/CVE-2026-67337","summary":"better-auth before 1.4.9 Two-Factor Authentication Bypass via 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.","published":"2026-08-01T12:22:18.034Z","modified":"2026-10-28T02:31:08.000302306Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"better-auth","fixedVersion":"1.4.9"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67337.json"},{"type":"ADVISORY","url":"https://github.com/better-auth/better-auth/security/advisories/GHSA-xg6x-h9c9-2m83"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67337"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/better-auth-before-two-factor-authentication-bypass-via-session-cookiecache"},{"type":"PACKAGE","url":"https://github.com/better-auth/better-auth"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:08.000302306Z"}}