CVE-2026-32738: libheif is a HEIF and AVIF file format decoder and encoder

Q: How do I fix CVE-2026-32738?

libheif: upgrade to 1.22.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-32738 being exploited?

CVE-2026-32738 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-32738 affect?

CVE-2026-32738 affects libheif. Severity is medium (CVSS 6.5). 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_s

Q: How urgent is CVE-2026-32738?

Priority 33/100. Public exploit reference

Routine

MEDIUM 6.5UPGRADE

CVE-2026-32738 is a medium-severity flaw (CVSS 6.5) affecting libheif. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 guaran

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-125, CWE-476
Published	2026-05-19
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: struktur

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-19 19:16 UTCPublished CVE record published
2026-07-24 09:10 UTCUpdated Record last modified

struktur libheif UPGRADE

Affected: < 1.22.0

Fixed in: 1.22.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libheif || rpm -q libheif || libheif --version

2. UPGRADE to 1.22.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libheif

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libheif

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-32738?

libheif: upgrade to 1.22.0. Exact commands for each OS are on this page.

Is CVE-2026-32738 being exploited?

CVE-2026-32738 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-32738 affect?

CVE-2026-32738 affects libheif. Severity is medium (CVSS 6.5). 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_s

How urgent is CVE-2026-32738?

Priority 33/100. Public exploit reference

Related CVEs

CVE-2026-49271 MEDIUM 6.5 UPGRADE libheif is a HEIF and AVIF file format decoder and encoder
CVE-2026-47247 HIGH 7.5 UPGRADE libheif is a HEIF and AVIF file format decoder and encoder
CVE-2026-47178 MEDIUM 6.1 UPGRADE libheif is a HEIF and AVIF file format decoder and encoder
CVE-2026-47251 MEDIUM 6.1 UPGRADE libheif is a HEIF and AVIF file format decoder and encoder
CVE-2026-47254 MEDIUM 6.1 UPGRADE libheif is a HEIF and AVIF file format decoder and encoder

References

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