directconn.c in the MSN protocol plugin in libpurple 2.7.6 through 2.7.8 in Pidgin before 2.7.9 allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via a short p2pv2 packet in a DirectConnect (aka direct connection) session.
libpurple in Pidgin before 2.7.4 does not properly validate the return value of the purple_base64_decode function, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via a crafted message, related to the plugins for MSN, MySpaceIM, XMPP, and Yahoo! and the NTLM authentication support.
The clientautoresp function in family_icbm.c in the oscar protocol plugin in libpurple in Pidgin before 2.7.2 allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via an X-Status message that lacks the expected end tag for a (1) desc or (2) title element.