The "process-execute" and "process-spawn" procedures did not free memory correctly when the execve() call failed, resulting in a memory leak. This could be abused by an attacker to cause resource exhaustion or a denial of service. This affects all releases of CHICKEN up to and including 4.11 (it will be fixed in 4.12 and 5.0, which are not yet released).
http://www.securityfocus.com/bid/92550
http://lists.nongnu.org/archive/html/chicken-announce/2016-08/msg00001.html