# CVE-2026-84383: libheif: libheif is a HEIF and AVIF file format decoder and encoder

CVE-2026-84383 is fixed in libheif on 1 platform, first by DEBIAN-CVE-2026-84383, released September 5, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-84383
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0072
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 18, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libheif Debian 14 | 1.23.2-1 | [DEBIAN-CVE-2026-84383](https://patchblox.com/security/data/fix/linux/debian-cve-2026-84383.md) | Sep 5, 2026 |
| Linux | libheif opensuse-leap 16.0 | 1.23.4-160000.1.1 | [OPENSUSE-SU-2026:21889-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21889-1.md) | Sep 20, 2026 |
| Linux | libheif sles 15.7 | 1.23.4-150700.3.21.1 | [SUSE-SU-2026:4276-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4276-1.md) | Sep 21, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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