The (1) fence_apc and (2) fence_apc_snmp programs, as used in (a) fence 2.02.00-r1 and possibly (b) cman, when running in verbose mode, allows local users to append to arbitrary files via a symlink attack on the apclog temporary file.

More... (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2008-4579)