The address parser code in Postfix 1.1.12 and earlier allows remote attackers to cause a denial of service (lock) via (1) a malformed envelope address to a local host that would generate a bounce and contains the “.!” string in the MAIL FROM or Errors-To headers, which causes nqmgr to lock up, or (2) via a valid MAIL FROM with a RCPT TO containing a “.!” string, which causes an instance of the SMTP listener to lock up.
distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000717
lists.grok.org.uk/pipermail/full-disclosure/2003-August/007693.html
marc.info/?l=bugtraq&m=106001525130257&w=2
marc.info/?l=bugtraq&m=106029188614704&w=2
secunia.com/advisories/9433
www.debian.org/security/2003/dsa-363
www.kb.cert.org/vuls/id/895508
www.linuxsecurity.com/advisories/engarde_advisory-3517.html
www.mandriva.com/security/advisories?name=MDKSA-2003:081
www.novell.com/linux/security/advisories/2003_033_postfix.html
www.redhat.com/support/errata/RHSA-2003-251.html
www.securityfocus.com/bid/8333
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A544