strukturag libheif up to 1.21.x AVIF File decode_mask_image heap-based overflow

Summaryinfo

A vulnerability classified as critical was found in strukturag libheif up to 1.21.x. Affected by this issue is the function MaskImageCodec::decode_mask_image of the component AVIF File Handler. The manipulation results in heap-based overflow. This vulnerability was named CVE-2026-32741. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in strukturag libheif up to 1.21.x. Affected is the function MaskImageCodec::decode_mask_image of the component AVIF File Handler. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

libheif is a HEIF and AVIF file format decoder and encoder. Versions 1.21.2 and below contain a heap buffer overflow in MaskImageCodec::decode_mask_image(). When decoding a HEIF file containing a mask image (mski), the function copies the full iloc extent data into a pixel buffer using memcpy(dst, data.data(), data.size()). The copy length data.size() is determined by the iloc extent in the file (attacker-controlled), while the destination buffer is sized based on the declared image dimensions. Because no upper-bound check exists on the data length, a crafted file whose iloc extent exceeds the pixel buffer allocation overflows the heap. The vulnerable single-memcpy branch is reached when the mskC property specifies bits_per_pixel = 8 and the ispe property declares an even width ≥ 64 (so that stride == width), with no changes to default security limits or external codec plugins required. This issue has been fixed in version 1.22.0.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-32741 since 03/13/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 316390 (Linux Distros Unpatched Vulnerability : CVE-2026-32741), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.22.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (316390). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• strukturag

Name

• libheif

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21

Website

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

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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