CVE-2025-68431

libheif is an HEIF and AVIF file format decoder and encoder. Prior to version 1.21.0, a crafted HEIF that exercises the overlay image item path triggers a heap buffer over-read in `HeifPixelImage::overlay()`. The function computes a negative row length (likely from an unclipped overlay rectangle or invalid offsets), which then underflows when converted to `size_t` and is passed to `memcpy`, causing a very large read past the end of the source plane and a crash. Version 1.21.0 contains a patch. As a workaround, avoid decoding images using `iovl` overlay boxes.

• https://github.com/strukturag/libheif/commit/b8c12a7b70f46c9516711a988483bed377b78d46

  security-advisories@github.com
• https://github.com/strukturag/libheif/releases/tag/v1.21.0

  security-advisories@github.com
• https://github.com/strukturag/libheif/security/advisories/GHSA-j87x-4gmq-cqfq

  security-advisories@github.com