Stack-based buffer overflow in the LiveJournal support (hooks/ljhook.cc) in CenterICQ 4.9.11 through 4.21.0, when using unofficial LiveJournal servers, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code by adding the victim as a friend and using long (1) username and (2) real name strings.
CenterICQ 4.20.0 and earlier creates temporary files with predictable file names, which allows local users to overwrite arbitrary files via a symlink attack on the gg.token.PID temporary file.