libpurple in Pidgin before 2.2.1 does not properly handle MSN nudge messages from users who are not on the receiver's buddy list, which allows remote attackers to cause a denial of service (crash) via a nudge message that triggers an access of "an invalid memory location."
Exploit prediction scoring system (EPSS) score
EPSS Score 0.014
EPSS Ranking 79.8%