SRC-2016-0022 : Microsoft Office Component FSupportSAEXTChar Use-After-Free Remote Code Execution Vulnerability



CVSS Score:

9.3, (AV:N/AC:M/Au:N/C:C/I:C/A:C)

Affected Vendors:


Affected Products:

Office Components

  • Office 2007
  • Office 2010

Vulnerability Details:

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Office. 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 handling of Microsoft Office binary files (.xls, .doc, .pst, .xlsb and .ppt). The SAEXT!ConvertVietToCP1258 function frees an instance of an object which is later accessed in SAEXT!FSupportSAEXTChar. An attacker could leverage this to execute arbitrary code under the context of the current user.

Vendor Response:

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

Disclosure Timeline:

  • 2016-01-19 – Vulnerability reported to vendor
  • 2016-01-29 – Vulnerability confirmed by the vendor
  • 2016-05-10 – Coordinated public release of advisory

Proof of Concept:


This vulnerability was discovered by Steven Seeley of Source Incite