CVE-2026-32738: Struktur Libheif

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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

• Struktur Libheif: before 1.22.0 (fixed in 1.22.0)

Published 2026-05-19. Last modified 2026-07-24.