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

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.

Scores

EPSS (exploitation in 30 days)

0.20% · top 90% of all CVEs (5 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.4.

Weakness

• CWE-436: Interpretation Conflict (opens in a new tab)All about CWE-436 and its CVEs

Affected products

• pnggroup · libpng

  • affected = 1.8.0

• pnggroup · libpng-apng

  • affected >= 1.6.49, <= 1.6.57

References (3)

• https://github.com/pnggroup/libpng/security/advisories/GHSA-c4v6-gxrq-6g2x (opens in a new tab)x_refsource_CONFIRM
• https://github.com/pnggroup/libpng/commit/faf06924688b62d7c1654b5ceddedbde66ffadb4 (opens in a new tab)x_refsource_MISC
• http://www.openwall.com/lists/oss-security/2026/05/15/21 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-40930](https://trackcve.app/badge/CVE-2026-40930.svg)](https://trackcve.app/cve/CVE-2026-40930)

Record last updated 4 Jun 2026, 16:37 UTC.