---
id: CVE-2026-84383
title: libheif is a HEIF and AVIF file format decoder and encoder
summary: >-
  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
  duplica…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: strukturag
product: libheif
affected:
  - 'libheif >= 1.22.0, < 1.23.2'
published: '2026-09-18'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T16:17:11.853'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84383'
references:
  - url: >-
      https://github.com/strukturag/libheif/commit/f4fb8bde4704ebb46e46ff9fb94407c9774153b2
    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-g89c-p67h-r497
    label: security-advisories@github.com
  - url: >-
      https://github.com/strukturag/libheif/security/advisories/GHSA-g89c-p67h-r497
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84383.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-84383'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2538121'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-84383'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84383'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
  - score-dispute
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-18T16:07:46.621200Z'
ingestedAt: '2026-09-18T16:45:41.392Z'
epss: 0.00608
epssPercentile: 0.46978
scores:
  nvd: 9.8
  vendor: 7.8
---

## Overview

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.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Critical · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84383.json)