CVE-2026-67335 better-auth before 1.6.2 OAuth State Validation Bypass
Attackers can bypass OAuth state validation to hijack sessions or link accounts when using cookie-backed state without PKCE.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-67335?
CVE-2026-67335 is a medium-severity authentication bypass vulnerability in better-auth, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
better-auth versions before 1.6.2 fail to validate the OAuth state parameter against the stored nonce when using cookie-backed state storage without PKCE. Attackers can forge the state parameter and supply an attacker-controlled authorization code to create authenticated sessions bound to the attacker's external identity or persistently link attacker accounts to victim profiles.
Weakness: CWE-287
Which versions are affected by CVE-2026-67335?
2 open source packages ship an affected version, including better-auth.
| Package | Affected | Fixed in |
|---|---|---|
better-auth npm | All versions | 1.6.2 |
better-auth npm | All versions | 1.6.2 |
How do I fix CVE-2026-67335?
Upgrade better-auth to 1.6.2 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-67335 being exploited?
There is no known exploitation of CVE-2026-67335 in the wild and no public exploit code.
Sources
Also known as GHSA-4hp3-gxv8-7g37, GHSA-wxw3-q3m9-c3jr.