Heap-based buffer overflow in smtpin.c for Exim 3 (exim3) before 3.36 and Exim 4 (exim4) before 4.21 may allow remote attackers to execute arbitrary code via an invalid (1) HELO or (2) EHLO argument with a large number of spaces followed by a NULL character and a newline, which is not properly trimmed before the "(no argument given)" string is appended to the buffer.

Exim 3.22 and earlier, in some configurations, does not properly verify the local part of an address when redirecting the address to a pipe, which could allow remote attackers to execute arbitrary commands via shell metacharacters.

Format string vulnerability in exim (3.22-10 in Red Hat, 3.12 in Debian and 3.16 in Conectiva) in batched SMTP mode allows a remote attacker to execute arbitrary code via format strings in SMTP mail headers.