CVE-2026-84383 — libheif: Heap buffer overflow in `scale_nearest_neighbor()` via duplicate Alpha planes from nested `iden`/`auxl` items

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
strukturag / libheif	affected >= 1.22.0, < 1.23.2

CWE

CWE-787

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/strukturag/libheif/security/advisories/GHSA-g89c-p67h-r497