Multiple vulnerabilities in the authentication mechanism of confd in FortiWeb versions 6.4.1, 6.4.0, 6.3.0 through 6.3.15, 6.2.0 through 6.2.6, 6.1.0 through 6.1.2, 6.0.0 thorugh 6.0.7, including an instance of concurrent execution using shared resource with improper synchronization and one of authentication bypass by capture-replay, may allow a remote unauthenticated attacker to circumvent the authentication process and authenticate as a legitimate cluster peer.