CVE-2011-1886 in Windows
Summary
win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP3 does not properly validate the arguments to functions, which allows local users to read arbitrary data from kernel memory via a crafted application that triggers a NULL pointer dereference, aka "Win32k Incorrect Parameter Validation Allows Information Disclosure Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.