The /proc handling (proc/base.c) Linux kernel 2.4 before 2.4.17 allows local users to cause a denial of service via unknown vectors that cause an invalid access of free memory.
http://www.securityfocus.com/bid/18173
http://www.debian.org/security/2006/dsa-1082
http://www.debian.org/security/2006/dsa-1070
http://www.debian.org/security/2006/dsa-1069
http://www.debian.org/security/2006/dsa-1067
http://secunia.com/advisories/20338
http://secunia.com/advisories/20202