CVE-2010-3962: Microsoft Internet Explorer use-after-free in CSS processing

CVE-2010-3962 · Severity: critical · CVSS 9.3 · Exploited in the wild · Published 2025-10-06

Internet Explorer is a legacy web browser used to access the internet and internal web applications. A critical vulnerability allows an attacker to take complete control of a user's computer if they visit a malicious website. This could lead to the theft of sensitive data, installation of malware, or total disruption of business operations. Because these versions of Internet Explorer are end-of-life, users should immediately switch to a modern, supported browser.

Technologies: Microsoft Edge, Microsoft Internet Explorer. Vendors: Microsoft.

Quick answers

Is CVE-2010-3962 exploited in the wild?
Yes. CVE-2010-3962 is known to be exploited in the wild, first recorded on 6 October 2025. Treat it as urgent.
How severe is CVE-2010-3962?
Critical severity, with a CVSS score of 9.3, published 6 October 2025.
Which products and versions are affected?
Microsoft Internet Explorer 6; Microsoft Internet Explorer 7; Microsoft Internet Explorer 8.
Is there a fix for CVE-2010-3962?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2010-3962 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2010-3962?
Check whether you run Microsoft Edge, Microsoft Internet Explorer, Microsoft Internet Explorer 6 or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A use-after-free vulnerability exists in Microsoft Internet Explorer 6, 7, and 8 due to improper handling of Cascading Style Sheets (CSS) token sequences and the 'clip' attribute. This is often referred to as an 'invalid flag reference' or uninitialized memory corruption issue. A remote attacker can exploit this by enticing a user to visit a malicious webpage, leading to arbitrary code execution in the context of the current user. The vulnerability was notably exploited in the wild as a zero-day in 2010. Microsoft released a patch under bulletin MS10-090, though the affected browser versions are now considered end-of-life.

Affected products

  • Microsoft Internet Explorer 6
  • Microsoft Internet Explorer 7
  • Microsoft Internet Explorer 8

Timeline

  • 2010-11-02: advisory: Microsoft released security advisory 2458511
  • 2010-11-01: exploited: Exploitation in the wild reported in November 2010
  • 2025-10-06: kev added: Added to CISA Known Exploited Vulnerabilities catalog

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