The counterToCSSValue function in CSSComputedStyleDeclaration.cpp in the Cascading Style Sheets (CSS) implementation in WebCore in WebKit before r82222, as used in Google Chrome before 11.0.696.43 and other products, does not properly handle access to the (1) counterIncrement and (2) counterReset attributes of CSSStyleDeclaration data provided by a getComputedStyle method call, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via crafted JavaScript code.