CVE 2007-2445
The png_handle_tRNS function in pngrutil.c in libpng before 1.0.25 and 1.2.x before 1.2.17 allows remote attackers to cause a denial of service (application crash) via a grayscale PNG image with a bad tRNS chunk CRC value.
See the 
CVE page on Mitre.org
for more details.
