Proofpoint Enterprise Protection contains a stored XSS vulnerability in the AdminUI. An unauthenticated attacker can send a specially crafted email with HTML in the subject which triggers XSS when viewing quarantined messages. This issue affects Proofpoint Enterprise Protection: from 8.20.0 before patch 4796, from 8.18.6 before patch 4795 and all other prior versions.
https://www.proofpoint.com/us/security/security-advisories/pfpt-sa-2023-0010