CVE-2026-125206: FFmpeg through 9.0.2 Out-of-Bounds Read via prores_ks Interlaced Alpha Encoding

FFmpeg through 9.0.2 contains an out-of-bounds read vulnerability in the proresks encoder's getalphadata() that reads before the blocks buffer for interlaced frames with odd heights. Attackers can supply video with alpha and odd height encoded to interlaced ProRes 4444, causing out-of-bounds memory to be encoded into the output alpha plane.