TippingPoint Zero Day Initiative

Apple Webkit SVG First-Letter Style Remote Code Execution Vulnerability

ZDI-10-142: August 5th, 2010


CVSS Score

Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 10065. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Apple Safari's Webkit. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the library's implementation of the first-letter style in the context of an SVG text element. Upon applying the style to this element, the library will calculate the height for determining the overflow for an inline box. While traversing the elements for the height, the library will utilize data from a non-existent linebox. Successful exploitation will lead to code execution under the context of the application.

Vendor Response

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

Disclosure Timeline

    2010-06-01 - Vulnerability reported to vendor
    2010-08-05 - Coordinated public release of advisory


This vulnerability was discovered by:
    wushi of team509