"Pidgin, Finch, Adium, Meebo, and Gaim are all vulnerable to a flaw that stems from a bug in Libpurple, library software for multi-protocol support that's used by many IM clients. The vulnerability stems from bugs in the software function that handles instant messages from the MSN network. The flaw was discovered by CORE Security whose advisory can be found here."
This article says Pidgin is 2.5.9 I looked and the new version I downloaded is 2.6.1
Always update your software when there are security updates.