Format string vulnerability in the log_message_cb function in otr-plugin.c in the Off-the-Record Messaging (OTR) pidgin-otr plugin before 3.2.1 for Pidgin might allow remote attackers to execute arbitrary code via format string specifiers in data that generates a log message.

The (1) otrl_base64_otr_decode function in src/b64.c; (2) otrl_proto_data_read_flags and (3) otrl_proto_accept_data functions in src/proto.c; and (4) decode function in toolkit/parse.c in libotr before 3.2.1 allocates a zero-length buffer when decoding a base64 string, which allows remote attackers to cause a denial of service (application crash) via a message with the value "?OTR:===.", which triggers a heap-based buffer overflow.

Use-after-free vulnerability in the create_smp_dialog function in gtk-dialog.c in the Off-the-Record Messaging (OTR) pidgin-otr plugin before 4.0.2 for Pidgin allows remote attackers to execute arbitrary code via vectors related to the "Authenticate buddy" menu item.

Integer overflow in proto.c in libotr before 4.1.1 on 64-bit platforms allows remote attackers to cause a denial of service (memory corruption and application crash) or execute arbitrary code via a series of large OTR messages, which triggers a heap-based buffer overflow.