CVE-2026-32738: struktur libheif Out-of-bounds Read

Vulnerability summary

CVE-2026-32738 is a medium (CVSS 6.5) Out-of-bounds Read vulnerability in struktur libheif. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 29.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 19-05-2026
   PublishedVulnerability first disclosed.
2. 19-05-2026
   Last modifiedVulnerability information updated.

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.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.
• CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.