FFmpeg versions 3.0 through 8.1.2 contain an out-of-bounds write vulnerability in the vf_swaprect video filter that allows attackers to corrupt heap memory by supplying a crafted NV12 video frame with odd width dimensions. The filter_frame() function reuses a temporary row buffer sized for plane 0's single-byte pixel step across all planes, causing an 18-byte memcpy into a 17-byte heap allocation when processing the two-byte-per-sample interleaved chroma plane of a 17x16 NV12 frame, resulting in heap corruption and process crash with potential for code execution.