gstreamer: gstreamer: rfbsrc/librfb Hextile heap out-of-bounds write with 16bpp framebuffer

A heap buffer overflow vulnerability was found in GStreamer's rfbsrc plugin. When a client connects to a malicious RFB/VNC server that advertises a 16bpp framebuffer and sends Hextile-encoded updates, the Hextile background fill path writes 32-bit pixel values into a buffer allocated for 16-bit...