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Vulnerability · Published Jun 4, 2026 · Assigned by GitHub_M

CVE-2026-40930LIBPNG: Chunk smuggling in push-mode APNG parser via unconsumed chunk body

Medium 5.4

In plain English

A medium-severity security flaw in libpng from pnggroup. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.2%top 89.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.21libpng1.6.59-r0ALPINE-CVE-2026-40930
Alpine:v3.22libpng1.6.59-r0ALPINE-CVE-2026-40930
Alpine:v3.23libpng1.6.58-r1ALPINE-CVE-2026-40930
Alpine:v3.24libpng1.6.58-r1ALPINE-CVE-2026-40930
Debian:12libpng1.61.6.37-4DEBIAN-CVE-2026-40930
Debian:13libpng1.61.6.37-4DEBIAN-CVE-2026-40930
Debian:14libpng1.61.6.37-4DEBIAN-CVE-2026-40930
Ubuntu:22.04:LTSlibpng1.61.6.37-3ubuntu0.6UBUNTU-CVE-2026-40930

Affected products (as reported)

VendorProductVersions
pnggroup libpng = 1.8.0
pnggroup libpng-apng >= 1.6.49, <= 1.6.57

Weakness: CWE-436 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

References