CVE-2024-34340: Authentication Bypass when using using older password hashes

Cacti provides an operational monitoring and fault management framework. Prior to version 1.2.27, Cacti calls compatpasswordhash when users set their password. compatpasswordhash use passwordhash if there is it, else use md5. When verifying password, it calls compatpasswordverify. In compatpasswordverify, passwordverify is called if there is it, else use md5. passwordverify and passwordhash are supported on PHP < 5.5.0, following PHP manual. The vulnerability is in compatpasswordverify. Md5-hashed user input is compared with correct password in database by $md5 == $hash. It is a loose comparison, not ===. It is a type juggling vulnerability. Version 1.2.27 contains a patch for the issue.