Mantis Bug Tracker (MantisBT) is an open source issue tracker. Due to incorrect use of loose (==) instead of strict (===) comparison in the authentication code in versions 2.27.1 and below.PHP type juggling will cause certain MD5 hashes matching scientific notation to be interpreted as numbers. Instances using the MD5 login method allow an attacker who knows the victim's username and has access to an account with a password hash that evaluates to zero to log in without knowing the victim's actual password, by using any other password with a hash that also evaluates to zero This issue is fixed in version 2.27.2.