# CVE-2026-67337: Better Auth two-factor authentication bypass via premature session caching

Source: https://junglewise.ai/threats/cve-2026-67337-better-auth-two-factor-authentication-bypass-via-premature  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-01. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-67337 · Severity: medium · CVSS 6.5 · Published 2026-08-01

Better Auth is an authentication framework that supports two-factor authentication (2FA) to protect user accounts. When session caching is enabled, a critical flaw allows attackers to bypass 2FA by using a cached session from before the second authentication factor is verified, gaining full access to protected application routes without completing the second factor.

Technologies: [better-auth (npm)](https://junglewise.ai/threats/technologies/better-auth). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-67337 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67337 being exploited in the wild.

**How severe is CVE-2026-67337?** Medium severity, with a CVSS score of 6.5, published 1 August 2026.

**Which products and versions are affected?** better-auth (npm) SEMVER:introduced=0,fixed=1.4.9.

**Is there a fix for CVE-2026-67337?** Yes. better-auth (npm): upgrade to 1.4.9 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-67337 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-67337?** Check whether you run better-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- better-auth (npm): upgrade to 1.4.9 or later

  ```sh
  npm install better-auth@1.4.9
  ```


## Technical details

This is an authentication bypass vulnerability (CWE-288) in Better Auth's session management. When both 2FA and session.cookieCache are enabled, the library caches a session as valid after the initial sign-in but before 2FA verification is complete. Subsequent session lookups return the cached session without re-evaluating the 2FA requirement, allowing an attacker with valid primary credentials to access authenticated routes without completing 2FA. The vulnerability affects version 1.4.5 and earlier; it was fixed in version 1.4.9. The attack requires valid primary credentials and does not require user interaction once primary authentication is obtained. As a temporary mitigation, disabling session.cookieCache when using 2FA can prevent exploitation.

## Affected products

- Better Auth better-auth < 1.4.9

## Identifiers

- CVE-2026-67337
- GHSA-xg6x-h9c9-2m83

## Timeline

- 2026-04-03: disclosed
- 2026-04-03: patched: Fix released in version 1.4.9

## References

- [https://github.com/better-auth/better-auth/security/advisories/GHSA-xg6x-h9c9-2m83](https://github.com/better-auth/better-auth/security/advisories/GHSA-xg6x-h9c9-2m83)
- [https://github.com/better-auth/better-auth](https://github.com/better-auth/better-auth)

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