CVE-2026-84448: strukturag libheif Out-of-bounds Read

Vulnerability summary

CVE-2026-84448 is a medium (CVSS 4.0) Out-of-bounds Read vulnerability in strukturag libheif. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 7.7% of scored vulnerabilities.

Timeline

1. 18-09-2026
   PublishedVulnerability first disclosed.
2. 24-09-2026
   Last modifiedVulnerability information updated.

Description

libheif is a HEIF and AVIF file format decoder and encoder. Prior to 1.23.2, the public heif_region_item_add_region_inline_mask_data() function in libheif/api/libheif/heif_regions.cc accepts mask_data_len without verifying that it equals the byte count required by width and height. A later heif_region_get_mask_image() call derives the read length from the region geometry, so an undersized stored buffer causes heif_region_get_inline_mask_image() to read beyond the heap allocation and copy adjacent bytes into the returned monochrome mask image. This can disclose heap data or crash an application that constructs region metadata through the writer API, while the file-parsing path is not affected because it validates the canonical mask size. This issue is fixed in version 1.23.2.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.
• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.