TippingPoint Zero Day Initiative

(Pwn2Own) Microsoft Windows TrueType Fonts Out-Of-Bounds Write Remote Code Execution Vulnerability

ZDI-15-388: August 11th, 2015


CVSS Score

Affected Vendors

Affected Products


Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Windows. 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 processing of the IUP instruction (opcode 0x31) in TrueType fonts. A crafted font can cause point patching to modify arbitrary addresses in the Windows kernel. This can be leveraged by an attacker to run arbitrary code in the context of SYSTEM.

Vendor Response

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

Disclosure Timeline

    2015-03-18 - Vulnerability reported to vendor
    2015-08-11 - Coordinated public release of advisory


This vulnerability was discovered by:
    KeenTeam's Jihui Lu and Peter Hlavaty