Forced login via unchecked OAuth state nonce
Published Aug 1, 2026 · Updated Aug 1, 2026
OAuth state validation bypass in Better Auth before 1.6.2 allows remote attackers to force attacker-bound sessions via OAuth callbacks. The cookie branch of parseGenericState decrypts oauth_state and checks expiry but fails to compare the callback state with the nonce from generateGenericState. Exploitation requires cookie-backed state storage, a live state cookie, user interaction, and a provider path without PKCE; account-linking flows grant persistent access to a victim profile.
Summary
What happened
OAuth state validation bypass in Better Auth before 1.6.2 allows remote attackers to force attacker-bound sessions via OAuth callbacks. The cookie branch of parseGenericState decrypts oauth_state and checks expiry but fails to compare the callback state with the nonce from generateGenericState. Exploitation requires cookie-backed state storage, a live state cookie, user interaction, and a provider path without PKCE; account-linking flows grant persistent access to a victim profile.
The record
- CVE
- CVE-2026-67335
- Published
- Aug 1, 2026
- Updated
- Aug 1, 2026
- Vendor
- Better Auth
- Product
- Better Auth
- Classifications
- CWE-287, T1078
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 1, 2026CVE publishedPublication date reported by the CVE source.
- Aug 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.6.2
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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