CVE-2004-0549: The WebBrowser ActiveX control, or the Internet Explorer HTML rendering engine (MSHTML), as used in Internet Explorer…

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 30 Jul 2004. It cites 1 public report, the first from 30 Jul 2004.

• learn.microsoft.com

How likely is exploitation in the next 30 days?

61.1%

EPSS score, percentile 99.2 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

Not scored

The CVE record carries no CVSS score.

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

The WebBrowser ActiveX control, or the Internet Explorer HTML rendering engine (MSHTML), as used in Internet Explorer 6, allows remote attackers to execute arbitrary code in the Local Security context by using the showModalDialog method and modifying the location to execute code such as Javascript, as demonstrated using (1) delayed HTTP redirect operations, and an HTTP response with a Location: header containing a "URL:" prepended to a "ms-its" protocol URI, or (2) modifying the location attribute of the window, as exploited by the Download.ject (aka Scob aka Toofer) using the ADODB.Stream object.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

• MS04-025 (Vendor advisory)

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline