CVE-2026-40930Network attack vector

Image content injection via APNG chunk smuggling

Published Jun 4, 2026 · Updated Jun 4, 2026

Interpretation conflict in PNG Development Group libpng 1.8.0 allows remote attackers to alter rendered APNG content via crafted files. Three discard paths in png_push_read_chunk clear the chunk-header flag without consuming the ignored chunk body and CRC, so png_process_data treats those bytes as a new header. A push-mode application must open the file; default CRC handling rejects it and interrupts rendering, while explicitly relaxed handling accepts attacker-chosen frame pixels.

CVSS severity5.4
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Interpretation conflict in PNG Development Group libpng 1.8.0 allows remote attackers to alter rendered APNG content via crafted files. Three discard paths in png_push_read_chunk clear the chunk-header flag without consuming the ignored chunk body and CRC, so png_process_data treats those bytes as a new header. A push-mode application must open the file; default CRC handling rejects it and interrupts rendering, while explicitly relaxed handling accepts attacker-chosen frame pixels.

The record

CVE
CVE-2026-40930
Published
Jun 4, 2026
Updated
Jun 4, 2026
Vendor
PNG Development Group
Product
libpng
Classifications
CWE-436, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 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== 1.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PNG Development Group · libpngversion== 1.8.0
PNG Development Group · APNG patch for libpngversion=>= 1.6.49, <= 1.6.57

Published CVSS scores

5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-436Interpretation Conflict
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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