An underflow read was found in pngcheckkeyword in pngwutil.c in libpng-1.2.54:

If the data of "key" is only ' ' (0x20), it will read a byte before the buffer in line 1288.

This issue impacts upstream versions 1.2.55, 1.0.65, 1.4.18, and 1.5.25 of libpng.

An attacker could possibly use this flaw to cause an out-of-bounds read by tricking an unsuspecting user into processing a specially crafted PNG image.

CVE assignment:

http://seclists.org/oss-sec/2015/q4/469

Upstream issue:

http://sourceforge.net/p/libpng/bugs/244/

Upstream patch:

http://sourceforge.net/p/libpng/code/ci/d9006f683c641793252d92254a75ae9b815b42ed/

Last updated 18 August 2026

The PNG reference library (aka libpng) before 1.0.43, and 1.2.x before 1.2.35, as used in pngcrush and other applications, allows context-dependent attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted PNG file that triggers a free of an uninitialized pointer in (1) the pngreadpng function, (2) pCAL chunk handling, or (3) setup of 16-bit gamma tables.

The pngpushreadzTXt function in pngpread.c in libpng 1.0.x before 1.0.58, 1.2.x before 1.2.48, 1.4.x before 1.4.10, and 1.5.x before 1.5.10 allows remote attackers to cause a denial of service (out-of-bounds read) via a large availin field value in a PNG image.