CVE-2010-3971
CriticalExploitedPublic exploitUse-after-free vulnerability in the CSharedStyleSheet::Notify function in the Cascading Style Sheets (CSS) parser in mshtml.dll, as used in Microsoft Internet Explorer 6 through 8 and other products, allows remote attackers to execute arbitrary code or cause a denial of service…
Published Dec 22, 2010 · Updated Apr 28, 2026
Key Facts
Patch immediately- CVE-2010-3971 is a critical-severity vulnerability (CVSS 9.3 v2) affecting Internet Explorer (Microsoft).
- It is exploited in the wild, listed in Industry KEV feed since Mar 8, 2011. Public exploit code is available.
- EPSS estimates a 82% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v2
9.3
AV:N/AC:M/Au:N/C:C/I:C/A:C
EPSS (30-day exploit likelihood)
82%
Higher than 99.6% of all scored CVEs
Exploited in the wild
Yes
1 catalog listing
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2010-3971 brief as a PDF
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Description
Use-after-free vulnerability in the CSharedStyleSheet::Notify function in the Cascading Style Sheets (CSS) parser in mshtml.dll, as used in Microsoft Internet Explorer 6 through 8 and other products, allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a self-referential @import rule in a stylesheet, aka "CSS Memory Corruption Vulnerability."
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Mar 8, 2011 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Internet ExplorerMicrosoft | 7, 8 | n/a |
Timeline
Publicly disclosed
Dec 22, 2010
Added to Industry KEV feed
Mar 8, 2011
Last updated
Apr 28, 2026
Weakness Type
- CWE-399
References
- advisory42510
- advisoryADV-2010-3156
- exploit20101208 IE CSS parser dos bug
- exploitMSF ms11_003_ie_css_import.rb
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Use-after-free vulnerability in the CSharedStyleSheet::Notify function in the Cascading Style Sheets (CSS) parser in mshtml.dll, as used in Microsoft Internet Explorer 6 through 8 and other products, allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a self-referenti…
Affected: Internet Explorer (Microsoft) versions 7, 8. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Mar 8, 2011.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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