GitHub Security Advisory (GHSA-wxw3-q3m9-c3jr)Vendor advisory
https://github.com/better-auth/better-auth/security/advisories/GHSA-wxw3-q3m9-c3jr CVE-2026-67335
MEDIUM
better-auth before 1.6.2 OAuth State Validation Bypass
Record summary
CVE-2026-67335 has a selected CVSS score of 6.0 (medium).
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.
Description source: CVE List
Exploitation context
CISA SSVC decision
ExploitationNone
AutomatableNo
Technical impactPartial
CISA Coordinator · SSVC 2.0.3 · Evaluated Aug 3, 2026 · Source: CVE List
Affected products and versions
1| Product | Source | Version range | Status |
|---|---|---|---|
better-authBrowse better-auth / better-authDefault status: unaffected | CVE List | Before 1.6.2 | affected |
| 1.6.2 | unaffected |
References
3nvd.nist.gov
https://nvd.nist.gov/vuln/detail/CVE-2026-67335 VulnCheck Advisory: better-auth before 1.6.2 OAuth State Validation BypassThird-party advisory
https://www.vulncheck.com/advisories/better-auth-before-oauth-state-validation-bypass