The notify function in pidgin-knotify.c in the pidgin-knotify plugin 0.2.1 and earlier for Pidgin allows remote attackers to execute arbitrary commands via shell metacharacters in a message.
Heap-based buffer overflow in a regular-expression parser in Mozilla Network Security Services (NSS) before 3.12.3, as used in Firefox, Thunderbird, SeaMonkey, Evolution, Pidgin, and AOL Instant Messenger (AIM), allows remote SSL servers to cause a denial of service (application crash) or possibly execute arbitrary code via a long domain name in the subject's Common Name (CN) field of an X.509 certificate, related to the cert_TestHostName function.