Heap-based buffer overflow in smtp_in.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.
http://www.exim.org/pipermail/exim-users/Week-of-Mon-20030811/057809.html
http://www.exim.org/pipermail/exim-users/Week-of-Mon-20030811/057720.html
http://www.exim.org/pipermail/exim-announce/2003q3/000094.html
http://www.debian.org/security/2003/dsa-376
http://packages.debian.org/changelogs/pool/main/e/exim4/exim4_4.34-10/changelog
http://packages.debian.org/changelogs/pool/main/e/exim/exim_3.36-13/changelog
http://marc.info/?l=vuln-dev&m=106264740820334&w=2
http://marc.info/?l=bugtraq&m=106252015820395&w=2
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000735