CVE-2026-33636

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.

Affected products

Libpng, Linuxmint, Red Os, Rocky Linux, Ubuntu

Libpng

< 1.6.56

Fix

Available

CVSS 3.1

7.6 HIGH

EPSS

0.7% (51th percentile)

Weakness

CWE-787, CWE-125

NVD status

Analyzed

Published

2026-03-26

No exploit for CVE-2026-33636 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.