In Yubico pam-u2f before 1.3.1, local privilege escalation can sometimes occur. This product implements a Pluggable Authentication Module (PAM) that can be deployed to support authentication using a YubiKey or other FIDO compliant authenticators on macOS or Linux. This software package has an issue that allows for an authentication bypass in some configurations. An attacker would require the ability to access the system as an unprivileged user. Depending on the configuration, the attacker may also need to know the user's password.