CVE-2026-67334 in better-auth
Summary
by MITRE • 08/01/2026
better-auth versions before 1.6.11 fail to delete cached sessions when removing users via admin, anonymous, or SCIM endpoints when secondaryStorage is configured and storeSessionInDatabase is false. Attackers can reuse deleted user session tokens to maintain authentication for up to seven days after account deletion.
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Analysis
by VulDB Data Team • 08/01/2026
This vulnerability affects better-auth versions prior to 1.6.11 and stems from a critical flaw in session management when users are deleted through various administrative endpoints. The issue occurs specifically when secondaryStorage is configured and storeSessionInDatabase is set to false, creating a persistent security gap that allows attackers to exploit deleted user sessions. The technical root cause lies in the improper handling of session cleanup during user deletion operations, where cached session tokens remain accessible even after account termination.
The operational impact of this vulnerability is significant as it enables attackers to maintain unauthorized access for up to seven days post-account deletion through reused session tokens. This represents a direct violation of authentication security principles and creates a window of opportunity for malicious actors to exploit compromised accounts. The vulnerability affects multiple deletion pathways including admin interfaces, anonymous endpoints, and SCIM integration points, amplifying the attack surface considerably.
From a cybersecurity perspective, this flaw aligns with CWE-613 Insufficient Session Expiration and CWE-287 Improper Authentication, as it allows persistent access after legitimate authentication should have been terminated. The vulnerability also maps to ATT&CK technique T1078 Valid Accounts, where adversaries leverage compromised or deleted accounts to maintain persistence within systems. The seven-day window provides ample time for attackers to conduct reconnaissance, data exfiltration, or lateral movement before the sessions eventually expire naturally.
The configuration dependency on secondaryStorage and storeSessionInDatabase parameters indicates a design flaw in session management logic that fails to properly invalidate cached sessions during user deletion operations. This creates a state inconsistency where the system recognizes a user as deleted but continues to honor existing session tokens stored in memory or cache layers. Organizations using this authentication library face potential data breaches, unauthorized access to sensitive resources, and compliance violations.
Mitigation strategies should prioritize immediate upgrade to better-auth version 1.6.11 or later where this issue has been addressed. Administrators should also implement monitoring for unusual authentication patterns and session reuse following user deletion events. Additional protective measures include configuring shorter session timeouts, implementing session invalidation policies, and conducting regular security audits of authentication systems. Organizations should review their session management configurations to ensure that storeSessionInDatabase is properly set based on their security requirements and risk tolerance levels.