CVE-2026-67327 affects better-auth versions >= 1.1.3 and < 1.6.22, as well as pre-release versions >= 1.7.0-beta.0 and < 1.7.0-beta.10. The vulnerability enables account takeover through a pre-account hijacking technique. An attacker registers an account using a victim's email address with an attacker-chosen password before the victim creates their account. The attacker's account remains unverified but retains the attacker-set password. When the legitimate victim later authenticates via magic-link or email-OTP passwordless flows, the account is marked as verified but the pre-existing attacker password is not removed and existing sessions are not revoked. This grants the attacker persistent access to the victim's account. The vulnerability requires open email/password registration to be enabled. Fixes are available in versions 1.6.22 and 1.7.0-beta.10.