What is CVE-2026-40930?

CVE-2026-40930 is a medium-severity vulnerability in Pnggroup Libpng, classified under CWE-436. CVSS score: 5.4/10. Published 2026-06-04.

How severe is CVE-2026-40930?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Pnggroup Libpng

CVE-2026-40930

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.

Published 2026-06-04 · last modified 2026-07-22.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.004 (27.7th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002

Affected products

Pnggroup Libpng — versions = 1.8.0
Pnggroup Libpng-Apng — versions >= 1.6.49, <= 1.6.57

Weakness classification (CWE)

CWE-436

References

Frequently asked questions

What is CVE-2026-40930?: CVE-2026-40930 is a medium-severity vulnerability in Pnggroup Libpng, classified under CWE-436. CVSS score: 5.4/10. Published 2026-06-04.
How severe is CVE-2026-40930?: Medium severity. CVSS v3 base score is 5.4 out of 10.