Security researchers have discovered a critical vulnerability in the popular server email client Exim that allows attackers to bypass protection and send malicious attachments. More than 1.5 million servers worldwide are at risk.
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Cybersecurity experts discovered a serious vulnerability in Exim software, one of the most widely used mail servers in the world, 10 days ago. reports Ars Technica: The vulnerability, identified as CVE-2024-39929, allows attackers to bypass standard protection mechanisms and send emails with executable attachments that could pose a serious threat to end users.
Po data According to cyberthreat analysis company Censys, of the more than 6.5 million publicly accessible SMTP servers currently online, 4.8 million (about 74%) are running Exim. More than 1.5 million Exim servers (about 31%) are running vulnerable versions of the software.
The vulnerability, CVE-2024-39929, has a severity rating of 9.1 out of 10 on the CVSS severity scale and is caused by an error in the handling of multiline headers as described in RFC 2231. Heiko Schlittermann, a member of the Exim development team, confirmed the vulnerability, calling it a “serious security issue.”
While there are currently no reports of the bug being actively exploited, experts warn of a high probability of targeted attacks in the near future. They recalled a case in 2020, when the Sandworm hacker group exploited another vulnerability in Exim (CVE-2019-10149) to launch mass attacks on servers.
Although a successful attack requires the end user to launch a malicious attachment, experts emphasize that social engineering methods remain one of the most effective ways to compromise systems. Experts recommend that Exim server administrators update their software to the latest version as soon as possible to protect their systems from potential attacks.
The vulnerability CVE-2024-39929 is present in all versions of Exim up to and including 4.97.1. A fix is available in Release Candidate 3 of version 4.98.
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