What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-04 · updated 2026-07-22
• Weakness: CWE-436

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 products

• pnggroup libpng: = 1.8.0
• pnggroup libpng-apng: from 1.6.49, <= 1.6.57

References

• https://github.com/pnggroup/libpng/commit/faf06924688b62d7c1654b5ceddedbde66ffadb4
• https://github.com/pnggroup/libpng/security/advisories/GHSA-c4v6-gxrq-6g2x
• http://www.openwall.com/lists/oss-security/2026/05/15/21

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