libpurple in Pidgin 2.1.0 through 2.2.1, when using HTML logging, allows remote attackers to cause a denial of service (NULL dereference and application crash) via a message that contains invalid HTML data, a different vector than CVE-2007-4996.
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.