CVE-2026-67335

MEDIUM 5.3

better-auth before 1.6.2 OAuth State Validation Bypass

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-287
Vendor	better-auth
Product	better-auth
Published	Aug 1, 2026

Stay Ahead of the Next One

Get instant alerts for better-auth better-auth

Be the first to know when new medium vulnerabilities affecting better-auth better-auth are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

better-auth / better-auth

0 < 1.6.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/better-auth/better-auth/security/advisories/GHSA-wxw3-q3m9-c3jr vulncheck.com: https://www.vulncheck.com/advisories/better-auth-before-oauth-state-validation-bypass

Credits

🔍 Jvr2022 🔍 alavesa