Multiple vulnerabilities in NetPBM 9.20 and earlier, and possibly other versions, may allow remote attackers to cause a denial of service or execute arbitrary code via "maths overflow errors" such as (1) integer signedness errors or (2) integer overflows, which lead to buffer overflows.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11463
http://www.securityfocus.com/bid/6979
http://www.redhat.com/support/errata/RHSA-2003-060.html
http://www.kb.cert.org/vuls/id/630433
http://www.debian.org/security/2003/dsa-263
http://marc.info/?l=bugtraq&m=104644687816522&w=2
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000656