A missing cryptographic step in the implementation of the hash digest algorithm in FortiMail may allow an unauthenticated attacker to tamper with signed URLs by appending further data which allowsÂ bypass of signatureÂ verification.
FortiMail 6.4.4 and below,
FortiMail 6.2.6 and below.
Upgrade to FortiMail version 7.0.0.
Upgrade to FortiMail version 6.4.5.