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CVE-2026-40930 pnggroup CVE debrief

A vulnerability was discovered in LIBPNG 1.8.0, a reference library for processing PNG raster image files. The issue lies in the push-mode APNG parser, where three inter-frame chunk discard paths clear the chunk-header flag without consuming the chunk body and CRC. This allows attacker-controlled bytes inside an ignored ancillary chunk to be reinterpreted as a fresh chunk header on the next call to `png_process_data`. The vulnerability has been fixed with commit [ref-4].

Vendor
pnggroup
Product
libpng
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-04
Original CVE updated
2026-06-04
Advisory published
2026-06-04
Advisory updated
2026-06-04

Who should care

Developers and users of applications that process PNG raster image files using LIBPNG 1.8.0 should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability has a CVSS score of 5.4 and is classified as MEDIUM severity. The CVSS vector is [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L]. The weakness is categorized as CWE-436.

Defensive priority

MEDIUM

Recommended defensive actions

  • Update LIBPNG to a version that includes the fix, such as applying commit [ref-4].
  • Review and update applications that use LIBPNG 1.8.0 to process PNG files.

Evidence notes

The CVE record [cve-org] and NVD detail [nvd] provide official information about the vulnerability. Additional references include [ref-4], [ref-5], and [ref-6].

Official resources

CVE-2026-40930 was published on 2026-06-04T16:16:36.633Z and modified on 2026-06-04T16:23:52.530Z.