CVE 2012-2864
Mesa, as used in Google Chrome before 21.0.1183.0 on the Acer AC700, Cr-48, and Samsung Series 5 and 5 550 Chromebook platforms, and the Samsung Chromebox Series 3, allows remote attackers to execute arbitrary code via unspecified vectors that trigger an "array overflow."
See the 
CVE page on Mitre.org
for more details.
