Exim vulnerability affecting 1.5M servers lets attackers attach malicious files

A critical vulnerability in the Exim mail transfer agent, tracked as CVE-2024-39929, has left over 1.5 million email servers exposed to attacks that can deliver malicious executable attachments to user accounts. Security researchers have highlighted the severity of this issue, as threat actors can easily bypass protections against such attachments, making it easier to distribute malware through emails. While there have been no reported active exploitations yet, the large number of vulnerable servers raises concerns about potential targeting. The vulnerability exists in Exim versions up to 4.97.1, with a fix available in the Release Candidate 3 of Exim 4.98. Although user interaction is required for the attack to succeed, social engineering tactics can still make it a significant threat. Admins are advised to prioritize updating their Exim servers to the latest secure version to mitigate the risk of exploitation.