libheif: Heap out-of-bounds read in libheif inline-mask region API (heif_region_item_add_region_inline_mask_data / heif_region_get_mask_image)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

18 Sep 2026 15:53:42 UTC

Source modified

24 Sep 2026 20:58:18 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 4.0 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L