The XmlImportExport plugin in MantisBT 1.2.17 and earlier allows remote attackers to execute arbitrary PHP code via a crafted (1) description field or (2) issuelink attribute in an XML file, which is not properly handled when executing the preg_replace function with the e modifier.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.