Vulnerability · Published May 19, 2026 · Assigned by GitHub_M

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

Medium 6.5

In plain English

A medium-severity out-of-bounds read in libheif from strukturag. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.3%top 77.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Alpine:v3.23	libheif	1.23.0-r0	ALPINE-CVE-2026-32738
Alpine:v3.24	libheif	1.22.2-r0	ALPINE-CVE-2026-32738
Debian:12	libheif	no fix listed	DEBIAN-CVE-2026-32738
Debian:14	libheif	1.23.1-1	DEBIAN-CVE-2026-32738
Ubuntu:25.10	libheif	1.20.2-1ubuntu0.4	UBUNTU-CVE-2026-32738
Ubuntu:26.04:LTS	libheif	1.21.2-3ubuntu0.1	UBUNTU-CVE-2026-32738

Affected products (as reported)

Vendor	Product	Versions
strukturag	libheif	< 1.22.0

Weakness: CWE-125, CWE-476 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

https://github.com/strukturag/libheif/security/advisories/GHSA-7f2h-cmpf-v9ww x_refsource_CONFIRM