strukturag libheif up to 1.23.1 Alpha Plane pixelimage.cc scale_nearest_neighbor out-of-bounds write

Summaryinfo

A vulnerability categorized as critical has been discovered in strukturag libheif up to 1.23.1. This issue affects the function HeifPixelImage::scale_nearest_neighbor of the file libheif/image/pixelimage.cc of the component Alpha Plane Handler. Such manipulation leads to out-of-bounds write. This vulnerability is documented as CVE-2026-84383. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in strukturag libheif up to 1.23.1. Affected by this issue is the function HeifPixelImage::scale_nearest_neighbor of the file libheif/image/pixelimage.cc of the component Alpha Plane Handler. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-84383 since 09/01/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 1.23.2 eliminates this vulnerability.

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Productinfo

Vendor

• strukturag

Name

• libheif

Version

• 1.23.0
• 1.23.1

Website

• Product: https://github.com/strukturag/libheif/

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