Proofpoint Enterprise Protection (PPS/PoD) before 8.16.4 contains a vulnerability that could allow an attacker to deliver an email message with a malicious attachment that bypasses scanning and file-blocking rules. The vulnerability exists because messages with certain crafted and malformed multipart structures are not properly handled.
A file-extension filtering vulnerability in Proofpoint Enterprise Protection (PPS / PoD), in the unpatched versions of PPS through 8.9.22 and 8.14.2 respectively, allows attackers to bypass protection mechanisms (related to extensions, MIME types, virus detection, and journal entries for transmitted files) by sending malformed (not RFC compliant) multipart email.