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Fencer Intel
medium 5.4

CVE-2026-40930 json

LIBPNG: Chunk smuggling in push-mode APNG parser via unconsumed chunk body

published 5mo ago modified 3mo ago also EUVD-2026-34287

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

LIBPNG is a reference library for use in applications that process PNG (Portable Network Graphics) raster image files. In version 1.8.0, three inter-frame chunk discard paths in the push-mode APNG parser clear the chunk-header flag without consuming the chunk body and CRC, allowing attacker-controlled bytes inside an ignored ancillary chunk to be reinterpreted as a fresh chunk header on the next call to `png_process_data`. Commit faf06924688b62d7c1654b5ceddedbde66ffadb4 fixes the issue.

Patch / fix

  • libpng1.6 Debian 14, Debian 13, Debian 12 1.6.37-4

debian advisories DEBIAN-CVE-2026-40930

  • libpng1.6 Ubuntu 22.04 LTS 1.6.37-3ubuntu0.6
  • libpng1.6 Ubuntu Pro 20.04 LTS 1.6.37-2ubuntu0.1~esm3

ubuntu advisories UBUNTU-CVE-2026-40930

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libpng hummingbird 1 1.6.58-1.hum1
  • libpng-tools hummingbird 1 1.6.58-1.hum1

red hat advisories RHSA-2026:20356

  • libpng Alpine 3.22, Alpine 3.21 1.6.59-r0
  • libpng Alpine 3.24, Alpine 3.23 1.6.58-r1

alpine advisories ALPINE-CVE-2026-40930

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-40930 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-40930 updated cvss 5.4

libpng: libpng: Data integrity and availability impact due to improper APNG chunk handling

  • Red Hat build of OpenJDK 1.8 java-17-openjdk, java-21-openjdk, java-21-openjdk-vanilla, java-1.8.0-openjdk-portable
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of OpenJDK 11 ELS java-11-openjdk, java-17-openjdk, java-21-openjdk, java-21-openjdk-vanilla, java-11-openjdk-portable, java-25-openjdk-portable
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat build of OpenJDK 17 java-17-openjdk, java-21-openjdk, java-21-openjdk-vanilla, java-17-openjdk-portable, java-25-openjdk-portable Red Hat build of OpenJDK 21 java-17-openjdk, java-21-openjdk, java-21-openjdk-vanilla, java-21-openjdk-portable, java-25-openjdk-portable Red Hat build of OpenJDK 25 java-25-openjdk-portable Red Hat Enterprise Linux 6 libpng Red Hat Enterprise Linux 7 libpng, firefox, libpng12, java-1.8.0-openjdk, java-1.8.0-openjdk-src, java-1.8.0-openjdk-demo, +4 more Red Hat Enterprise Linux 8 libpng, firefox, libpng12, libpng15, thunderbird, mingw-libpng, +65 more
    +4 more products
    Red Hat Enterprise Linux 9 libpng, firefox, libpng15, firefox-x11, thunderbird, java-17-openjdk, +84 more Red Hat Enterprise Linux 10 libpng, firefox, thunderbird, java-21-openjdk, java-25-openjdk Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images libpng 1.6.58-1.hum1, libpng-tools 1.6.58-1.hum1
    fixed: vendor fix RHSA-2026:20356
  • Red Hat Hardened Images boost
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

Affected products

  • pnggroup libpng
  • pnggroup libpng-apng

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.