Unspecified vulnerability in the client in Skype 5.x before 5.1.0.922 on Mac OS X allows remote authenticated users to execute arbitrary code or cause a denial of service (application crash) via a crafted message.
http://www.vupen.com/english/advisories/2011/1192
http://www.theregister.co.uk/2011/05/06/skype_for_mac_critical_vulnerability/
http://www.securityfocus.com/bid/47747
http://www.purehacking.com/blogs/gordon-maddern/skype-0day-vulnerabilitiy-discovered-by-pure-hacking
http://secunia.com/advisories/44522
http://isc.sans.edu/diary.html?storyid=10837
http://blogs.skype.com/security/2011/05/security_vulnerability_in_mac.html