Gstreamer1-plugins-bad-free: gstreamer: heap buffer overflow via crafted vnc server rectangle in librfb

A heap buffer overflow vulnerability was found in GStreamer's librfb (RFB/VNC client). The rectangle bounds check incorrectly validates area rather than individual dimensions, allowing a malicious VNC server to send a rectangle that extends beyond the framebuffer. A remote attacker could set up a malicious VNC server and trick a user into connecting, resulting in an out-of-bounds heap write that could lead to code execution or a crash.