main/acl.c in Asterisk Open Source 1.6.0.x before 1.6.0.25, 1.6.1.x before 1.6.1.17, and 1.6.2.x before 1.6.2.5 does not properly enforce remote host access controls when CIDR notation "/0" is used in permit= and deny= configuration rules, which causes an improper arithmetic shift and might allow remote attackers to bypass ACL rules and access services from unauthorized hosts.
https://exchange.xforce.ibmcloud.com/vulnerabilities/56552
http://www.vupen.com/english/advisories/2010/0475
http://www.securityfocus.com/bid/38424
http://www.securityfocus.com/archive/1/509757/100/0/threaded
http://secunia.com/advisories/39096
http://secunia.com/advisories/38752
http://lists.fedoraproject.org/pipermail/package-announce/2010-March/037679.html
http://downloads.asterisk.org/pub/security/AST-2010-003.html
http://downloads.asterisk.org/pub/security/AST-2010-003-1.6.2.diff
http://downloads.asterisk.org/pub/security/AST-2010-003-1.6.1.diff
http://downloads.asterisk.org/pub/security/AST-2010-003-1.6.0.diff