CVE-2026-96611

FFmpeg before 9.0 has a signed integer overflow in libavformat/mov.c. In mov_read_ispe(), uint32_t width/height values from a crafted HEIF ispe box are stored into signed int fields without bounds checking, allowing values exceeding INT_MAX to become negative. In read_image_grid(), accumulating these values causes signed integer overflow (undefined behavior per C17 section 6.5), which on x86 wraps to a small positive value, bypassing downstream validity checks.

• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/059eb2e853c1f62b8df1b73be9318061a7a21b0bPatch
• https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23455Issue Tracking