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.

Urgent
CVSS
9.8
critical
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0072
54th percentile

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

ProductFixed inFixReleased
Linux
libheif · Debian 14 1.23.2-1 DEBIAN-CVE-2026-84383 Sep 5, 2026
libheif · opensuse-leap 16.0 1.23.4-160000.1.1 OPENSUSE-SU-2026:21889-1 Sep 20, 2026
libheif · sles 15.7 1.23.4-150700.3.21.1 SUSE-SU-2026:4276-1 Sep 21, 2026

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