---
id: CVE-2026-67335
title: >-
  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
summary: >-
  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
  authoriz…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N'
cwe:
  - CWE-287
published: '2026-08-01'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:34:34.997'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67335'
references:
  - url: >-
      https://github.com/better-auth/better-auth/security/advisories/GHSA-wxw3-q3m9-c3jr
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/better-auth-before-oauth-state-validation-bypass
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00283
epssPercentile: 0.18574
ingestedAt: '2026-08-02T08:18:07.705Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.