Kimai before 2.58.0 contains an authentication bypass vulnerability where password reset links remain valid after password changes because the LoginLink signature covers only the user id, not the password hash. Attackers who intercept or cache a password reset link can use it up to 2 additional times within a 1-hour window to log in as the user even after the legitimate user has changed their password.

Kimai versions before 2.58.0 contain an authentication bypass vulnerability tracked as CVE-2026-80196. The flaw exists because the LoginLink signature used in password reset links only covers the user ID and not the password hash. This means that even after a user changes their password, previously issued reset links remain valid. An attacker who intercepts or caches a password reset link can exploit it up to 2 additional times within a 1-hour window. This allows unauthorized login as the affected user despite the legitimate password change. The vulnerability poses a significant risk to user account security and session integrity. A fix has been released in Kimai version 2.58.0. Users are strongly advised to upgrade immediately to mitigate the risk.