TippingPoint Zero Day Initiative

Microsoft Internet Explorer Multiple CSS Imports Memory Corruption Vulnerability

ZDI-06-026: August 8th, 2006


Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 4606. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows attackers to execute arbitrary code on vulnerable installations of Microsoft Internet Explorer. User interaction is required to exploit this vulnerability in that the target must visit a malicious page.

The specific flaw exists due to improper garbage collection when multiple "imports" are used on a "styleSheets" collection. Crafting a long chain of CSS imports in an HTML document results in a memory corruption eventually leading to code execution.

Vendor Response

Microsoft has issued an update to correct this vulnerability. More details can be found at:

Disclosure Timeline

    2006-06-14 - Vulnerability reported to vendor
    2006-08-08 - Coordinated public release of advisory


This vulnerability was discovered by:
    Sam Thomas