---
id: CVE-2026-84448
title: libheif is a HEIF and AVIF file format decoder and encoder
summary: >-
  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…
severity: medium
cvss: 4
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L'
cwe:
  - CWE-125
  - CWE-131
vendor: strukturag
product: libheif
affected:
  - libheif < 1.23.2
published: '2026-09-18'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:18:55.407'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84448'
references:
  - url: >-
      https://github.com/strukturag/libheif/commit/646d85fbf5bd18fc3cdc516e915e59072de2d510
    label: security-advisories@github.com
  - url: 'https://github.com/strukturag/libheif/releases/tag/v1.23.2'
    label: security-advisories@github.com
  - url: >-
      https://github.com/strukturag/libheif/security/advisories/GHSA-p58j-h3vm-3fp5
    label: security-advisories@github.com
  - url: >-
      https://github.com/strukturag/libheif/security/advisories/GHSA-p58j-h3vm-3fp5
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-24T20:58:16.283291Z'
epss: 0.00186
epssPercentile: 0.07358
ingestedAt: '2026-09-18T16:45:41.395Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.