Better Auth Has Two-Factor Authentication Bypass via Premature Session Caching (session.cookieCache)GHSA-xg6x-h9c9-2m83
GHSA-xg6x-h9c9-2m83 is a CWE-288 vulnerability in better-auth. A fix is available for better-auth — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-xg6x-h9c9-2m83.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
better-authnpmDescription
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | better-auth | all versions | 1.4.9npm install better-auth@1.4.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for better-auth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update better-auth to 1.4.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xg6x-h9c9-2m83 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-xg6x-h9c9-2m83 in your dependencies?
Find it across npm, including transitive dependencies.