CVE-2010-4344: Exim Heap-Based Buffer Overflow Vulnerability

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2022-03-25. EPSS: 71.7% chance of exploitation in the next 30 days.

Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70 allows remote attackers to execute arbitrary code via an SMTP session that includes two MAIL commands in conjunction with a large message containing crafted headers, leading to improper rejection logging.

Affected products

• Canonical Ubuntu Linux: version 6.06 only; version 8.04 only; version 9.10 only
• Debian Debian Linux: version 5.0 only
• Exim Exim: before 4.70 (fixed in 4.70)
• Opensuse Opensuse: version 11.1 only; version 11.2 only; version 11.3 only

Published 2010-12-14. Last modified 2026-06-16.