Buffer overflow in Skype for Windows 1.1.x.0 through 1.4.x.83 allows remote attackers to execute arbitrary code via (1) callto:// and (2) skype:// links, or (3) a non-standard VCARD, possibly due to an underlying error in the SysUtils.WideFmtStr Delphi routine.
Skype for Windows 1.2.0.0 to 1.2.0.46 allows local users to bypass the identity check for an authorized application, then call arbitrary Skype API functions by modifying or replacing that application.