CVE-2026-84383

libheif is a HEIF and AVIF file format decoder and encoder. From 1.22.0 until 1.23.2, a crafted HEIF, HEIC, or AVIF item graph using nested iden and auxl references can make HeifPixelImage::transfer_channel_from_image_as() append duplicate Alpha planes with different bit depths to m_storage. HeifPixelImage::scale_nearest_neighbor() in libheif/image/pixelimage.cc allocates the destination Alpha plane using the first plane's 8-bit depth, then iterates a later 10-bit or 12-bit Alpha component and writes uint16_t samples into the same 8-bit allocation. The output geometry controls the overflow extent and the encoded sample values control the data written, allowing a remote file processed by heif_decode_image() to cause a heap out-of-bounds write. This issue is fixed in version 1.23.2.

• https://github.com/strukturag/libheif/commit/f4fb8bde4704ebb46e46ff9fb94407c9774153b2
• https://github.com/strukturag/libheif/releases/tag/v1.23.2
• https://github.com/strukturag/libheif/security/advisories/GHSA-g89c-p67h-r497
• https://github.com/strukturag/libheif/security/advisories/GHSA-g89c-p67h-r497