CVE-2026-32739Public exploitNetwork attack vector

Worker hang via stalled sample-duration loop

Published May 19, 2026 · Updated May 19, 2026

Infinite loop in libheif 1.21.2 and earlier allows remote attackers to hang image-processing workers via a crafted HEIF sequence file. Box_stts::get_sample_duration() never increments its entry index; a zero sample_count also leaves sample_idx unchanged, so parsing never exits. Any application that opens the file can lose a worker indefinitely while the process remains alive and consumes a CPU core.

CVSS severity6.5
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in libheif 1.21.2 and earlier allows remote attackers to hang image-processing workers via a crafted HEIF sequence file. Box_stts::get_sample_duration() never increments its entry index; a zero sample_count also leaves sample_idx unchanged, so parsing never exits. Any application that opens the file can lose a worker indefinitely while the process remains alive and consumes a CPU core.

The record

CVE
CVE-2026-32739
Published
May 19, 2026
Updated
May 19, 2026
Vendor
Struktur AG
Product
libheif
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 19, 2026CVE publishedPublication date reported by the CVE source.
  2. May 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.22.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Struktur AG · libheifversion=< 1.22.0

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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