CVE-2026-40930CWE-436

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

Medium · published June 4, 2026

CVSS v3.1
5.4
EPSS
0%
Percentile
28.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00355 · 28.0th percentile
Weakness
CWE-436 · Interpretation Conflict
Published
2026-06-04T14:34Z
EPSS history
Timeline
  • 04 JUN 14:34Z
    LIBPNG: Chunk smuggling in push-mode APNG parser via unconsumed chunk body
    cvelistv5