What is CVE-2026-32739?

CVE-2026-32739 is a medium-severity vulnerability in Struktur Libheif, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 6.5/10. Published 2026-05-19.

How severe is CVE-2026-32739?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Struktur Libheif

CVE-2026-32739

libheif is a HEIF and AVIF file format decoder and encoder. In versions 1.21.2 and below, a crafted 800-byte HEIF sequence file causes an infinite loop in Box_stts::get_sample_duration(), consuming 100% CPU indefinitely with zero progress, leading to DoS. The loop has no iteration limit or timeout and is triggered during file open (parsing) - before any user interaction or image decoding. The process stays alive (no crash, no error logged), making it invisible to crash-based monitoring. This issue has been fixed in version 1.22.0.

EPSS: 0.003 (24.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

Affected products

Struktur Libheif
Strukturag Libheif — versions < 1.22.0

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-32739?: CVE-2026-32739 is a medium-severity vulnerability in Struktur Libheif, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 6.5/10. Published 2026-05-19.
How severe is CVE-2026-32739?: Medium severity. CVSS v3 base score is 6.5 out of 10.