Better Auth Has Two-Factor Authentication Bypass via Premature Session Caching (session.cookieCache)
Summary
Under 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.
Description
When 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.
However, 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.
This results in a situation where session validity can be established before all authentication constraints are satisfied.
Impact
An attacker (or user) with valid primary credentials may gain access to protected application routes without completing the required second authentication factor.
Any application using better-auth with both two-factor authentication and session cookie caching enabled may be affected.
Mitigation
- Upgrade to a version of
better-auththat includes the fix for this issue. - Ensure that session caching does not treat sessions as fully authenticated until all required authentication steps, including 2FA, are completed.
- As a temporary workaround, disable
session.cookieCachewhen using two-factor authentication.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | better-auth | < 1.4.9 | 1.4.9 |
References
- CVSS vector
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- Weakness (CWE)
CWE-288- Platform
- npm
- Package
better-auth- Disclosed
- 03.04.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-xg6x-h9c9-2m83 - CC BY 4.0
Vulnerability history: better-auth
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 22
- First → latest
- 12.2024 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 14
- Medium 3
- Low 3
Disclosures per year
- 2024: 1
- 2025: 8
- 2026: 13
-
Better Auth Has Two-Factor Authentication Bypass via Premature Session Caching (session.cookieCache) this entry
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