The mlfi_envrcpt function in spamass-milter.cpp in SpamAssassin Milter Plugin 0.3.1, when using the expand option, allows remote attackers to execute arbitrary system commands via shell metacharacters in the RCPT TO field of an email message.
https://savannah.nongnu.org/bugs/?29136
https://exchange.xforce.ibmcloud.com/vulnerabilities/56732
https://bugzilla.redhat.com/show_bug.cgi?id=572117
http://www.vupen.com/english/advisories/2010/0837
http://www.vupen.com/english/advisories/2010/0683
http://www.vupen.com/english/advisories/2010/0559
http://www.securitytracker.com/id?1023691
http://www.debian.org/security/2010/dsa-2021
http://secunia.com/advisories/39265
http://secunia.com/advisories/38956
http://secunia.com/advisories/38840
http://lists.fedoraproject.org/pipermail/package-announce/2010-April/038777.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-April/038572.html
http://lists.fedoraproject.org/pipermail/package-announce/2010-April/038535.html