Vulnerability Note VU#29795

HHOpen ActiveX Control buffer overflow in OpenHelp method

Original Release date: 31 Oct 2000 | Last revised: 01 Nov 2000



The HHOpen ActiveX control (hhopen.ocx) has a buffer overflow in the OpenHelp method. Because the control is marked safe-for-scripting, an attacker may be able to script this control and exploit the vulnerability when you visit a web page.

The classID for the vulnerable control is: {130D7743-5F5A-11D1-B676-00A0C9697233}.


An attacker may be able to exploit a buffer overflow in the HHOpen ActiveX control and execute arbitrary code on the system of the person visiting a malicious web page.


Apply a patch

Apply the patch provided by Microsoft in Security Bulletin MS99-037. This patch sets the kill bit which prevents the control from being loaded by Internet Explorer.

Disable "Script ActiveX controls marked safe for scripting"

In your Internet Explorer security settings, set this option to "disable" or "prompt".

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
MicrosoftAffected-31 Oct 2000
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



This document was written by Cory F Cohen.

Other Information

  • CVE IDs: Unknown
  • Date Public: 10 Sep 99
  • Date First Published: 31 Oct 2000
  • Date Last Updated: 01 Nov 2000
  • Severity Metric: 12.66
  • Document Revision: 8


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