CVE-2026-125259: FFmpeg through 9.0.2 Heap Buffer Overflow via ProRes prores_ks Encoder

FFmpeg through 9.0.2 contains an integer overflow vulnerability in ffproreskostyaencodeinit() that miscalculates framesizeupperbound using 32-bit arithmetic for large frame dimensions. Attackers can supply a high-resolution video transcoded with the proresks encoder, causing encodeframe() to write slices past an undersized packet buffer and corrupt heap memory.