MantisBT before 1.2.19 and 1.3.x before 1.3.0-beta.2 does not properly restrict access to /*/install.php, which allows remote attackers to obtain database credentials via the install parameter with the value 4.
https://www.mantisbt.org/bugs/view.php?id=17939
https://www.mantisbt.org/bugs/view.php?id=17937
https://www.htbridge.com/advisory/HTB23243
https://exchange.xforce.ibmcloud.com/vulnerabilities/100211