The qtdemux_tag_add_str_full function in gst/isomp4/qtdemux.c in gst-plugins-good in GStreamer before 1.10.3 allows remote attackers to cause a denial of service (out-of-bounds read and crash) via a crafted tag value.
The vmnc decoder in the gstreamer does not initialize the render canvas, which allows remote attackers to obtain sensitive information as demonstrated by thumbnailing a simple 1 frame vmnc movie that does not draw to the allocated render canvas.
GStreamer before 1.4.5, as used in Mozilla Firefox before 38.0, Firefox ESR 31.x before 31.7, and Thunderbird before 31.7 on Linux, allows remote attackers to cause a denial of service (buffer over-read and application crash) or possibly execute arbitrary code via crafted H.264 video data in an m4v file.