CVE-2026-32738: libheif has a Heap OOB Read/SEGV Crash via Zero samples_per_chunk

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-19 · updated 2026-07-24
Weakness: CWE-125

Description

libheif is a HEIF and AVIF file format decoder and encoder. In versions 1.21.2 and below, a crafted 792-byte HEIF sequence file with samples_per_chunk=0 in the stsc box causes an unsigned integer underflow in the Chunk constructor (m_last_sample = 0 + 0 - 1 = UINT32_MAX), mapping all samples to an empty chunk and resulting in a denial of service. When any sample is accessed, the library reads from index 0 of an empty std::vector, causing a guaranteed SEGV (null-page read). The file parses successfully without producing an error; the crash occurs on the first frame access. This issue has been fixed in version 1.22.0.

Affected products

strukturag libheif: before 1.22.0 — fixed in 1.22.0

How to fix

Upgrade to a fixed version: strukturag libheif 1.22.0. Check the vendor advisory for mitigations.

References

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