CVE-2020-28024: Exim

Critical severity, CVSS 9.8. EPSS: 4.2% chance of exploitation in the next 30 days.

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smtp_ungetc was only intended to push back characters, but can actually push back non-character error codes such as EOF.

Affected products

• Exim Exim: from 4.00, before 4.94.2 (fixed in 4.94.2)

Published 2021-05-06. Last modified 2026-06-17.