Hello. Today we're releasing Security Advisory 2501696, which describes a publicly disclosed scripting vulnerability affecting all versions of Microsoft Windows. The main impact of the vulnerability is unintended information disclosure. We're aware of published information and proof-of-concept code that attempts to exploit this vulnerability, but we haven't seen any indications of active exploitation.
The vulnerability lies in the MHTML (MIME Encapsulation of Aggregate HTML) protocol handler, which is used by applications to render certain kinds of documents. The impact of an attack on the vulnerability would be similar to that of server-side cross-site-scripting (XSS) vulnerabilities. For instance, an attacker could construct an HTML link designed to trigger a malicious script and somehow convince the targeted user to click it. When the user clicked that link, the malicious script would run on the user's computer for the rest of the current Internet Explorer session. Such a script might collect user information (eg., email), spoof content displayed in the browser, or otherwise interfere with the user's experience.
