Format string vulnerability in the NSRunAlertPanel function in eBay Skype for Mac 1.5.*.79 and earlier allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a malformed Skype URL, as originally reported to involve a null dereference.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.