How severe is CVE-2026-32738?

CVE-2026-32738 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-32738 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-32738?

CVE-2026-32738 affects Struktur Libheif. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-32738?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-32738 have an EU (EUVD) identifier?

Yes. CVE-2026-32738 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30972.

When was CVE-2026-32738 published?

CVE-2026-32738 was published on 2026-05-19 and last updated on 2026-06-17.

CVE-2026-32738

CVE-2026-32738 is a medium-severity vulnerability in Struktur Libheif with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (22nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30972
Weakness: CWE-125
Affected product: Struktur Libheif
Published: 2026-05-19
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-32738?: 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.
How severe is CVE-2026-32738?: CVE-2026-32738 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-32738 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-32738?: CVE-2026-32738 affects Struktur Libheif. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-32738?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-32738 have an EU (EUVD) identifier?: Yes. CVE-2026-32738 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30972.
When was CVE-2026-32738 published?: CVE-2026-32738 was published on 2026-05-19 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:struktur:libheif:*:*:*:*:*:*:*:*

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