The msn_emoticon_msg function in slp.c in the MSN protocol plugin in libpurple in Pidgin before 2.7.0 allows remote authenticated users to cause a denial of service (NULL pointer dereference and application crash) via a custom emoticon in a malformed SLP message.
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.