🛡️ CVE-2026-67337 — better-auth

🔴 CVSS 9.5 — Critical ✅ No Known Exploit CWE-288 NVD
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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-auth that 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.cookieCache when using two-factor authentication.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

Weakness class

CVE-2026-67337 is classified as CWE-288: Authentication Bypass Using an Alternate Path. A secondary route into the application skips the authentication that the primary route enforces.

Affected software

CVE-2026-67337 is recorded against 2 packages.

  • better-auth
  • unknown

Timeline and source

Published on 3 April 2026 and last revised on 2 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Package)

Details

Severity CRITICAL
CVSS Score 9.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CWE CWE-288
Public Exploit ✅ No
Source NVD
Published 2026-04-03
Updated 2026-08-12
Modified 2026-08-02
Fix URL N/A

Affected Packages

Software From version Fixed in
better-auth — —
unknown — —

Similar Threats

Exploit Protection

Are you running better-auth?

CVE-2026-67337 carries CVSS 9.5 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

Check My Site For CVE-2026-67337 →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.