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Fencer Vulns
medium 5.4

CVE-2026-40930 json

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

published 2026-06-04 5 mo ago modified 2026-07-22 3 mo 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

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
5 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 Vulns 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.