CVE-2024-43461
Microsoft Windows MSHTML Platform Spoofing Vulnerability
Description
CVE-2024-43461 is a high-severity spoofing vulnerability in the Windows MSHTML Platform that affects a wide range of Microsoft Windows versions, including Windows 10, Windows 11, and Windows Server editions from 2008 through 2022. The MSHTML platform (also known as Trident), which powers Internet Explorer and is used by various Windows applications for HTML rendering, contains a flaw that allows attackers to spoof content displayed to the user. With a CVSS score of 8.8 and an EPSS probability of 9.76% (92.8th percentile), this vulnerability has been added to CISA's Known Exploited Vulnerabilities catalog with a remediation deadline of October 7, 2024.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 10 1507 | < 10.0.10240.20766 |
| microsoft | windows 10 1607 | < 10.0.14393.7336 |
| microsoft | windows 10 1809 | < 10.0.17763.6293 |
| microsoft | windows 10 21h2 | < 10.0.19044.4894 |
| microsoft | windows 10 22h2 | < 10.0.19045.4894 |
| microsoft | windows 11 21h2 | < 10.0.22000.3197 |
| microsoft | windows 11 22h2 | < 10.0.22621.4169 |
| microsoft | windows 11 23h2 | < 10.0.22621.4169; < 10.0.22631.4169 |
| microsoft | windows 11 24h2 | < 10.0.26100.1742 |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows server 2016 | < 10.0.14393.7336 |
| microsoft | windows server 2019 | < 10.0.17763.6293 |
| microsoft | windows server 2022 | < 10.0.20348.2700 |
| microsoft | windows server 2022 23h2 | < 10.0.25398.1128 |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-43461(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-43461(US Government Resource)
Weakness Type
No specific CWE has been assigned to CVE-2024-43461 by NVD. The vulnerability is a spoofing flaw in the Windows MSHTML Platform that allows attackers to manipulate how content is presented to the user. The MSHTML rendering engine processes HTML content and is deeply integrated into Windows, used not only by Internet Explorer but also by Outlook, Windows Search, and numerous third-party applications that embed web content. The spoofing vulnerability allows an attacker to craft content that misrepresents its true nature — for example, disguising a malicious file download as a legitimate document or making a dangerous URL appear trustworthy. This type of vulnerability exploits user trust in the visual presentation of content rather than attacking the underlying system directly, making it particularly effective for social engineering attacks.
Impact Analysis
The exploitation of CVE-2024-43461 impacts all three security dimensions significantly. Confidentiality is fully compromised because the spoofing capability allows attackers to trick users into submitting credentials to attacker-controlled endpoints, downloading malicious files they believe are legitimate, or clicking links that redirect to phishing pages. Integrity is completely affected as the spoofing can manipulate the user's perception of file types, origins, and content, leading them to execute malicious payloads or approve actions they would otherwise reject. Availability faces high risk since successful exploitation can lead to malware installation, ransomware deployment, or system compromise that disrupts normal operations.
Although user interaction is required (the victim must view or interact with the spoofed content), the MSHTML platform is invoked by many Windows applications beyond just Internet Explorer, broadening the attack surface considerably. Outlook's email rendering, Windows Search indexing, and any application that uses MSHTML for HTML processing can serve as exploitation vectors. The EPSS score of 9.76% (92.8th percentile) indicates substantial exploitation activity. The KEV entry lists ransomware association as "Unknown." The breadth of affected Windows versions — from Windows Server 2008 through Windows 11 24H2 — means virtually every Windows deployment is potentially vulnerable, making this a high-priority patch for enterprise environments.
Exploit Maturity
CVE-2024-43461 is confirmed to be actively exploited in the wild, as evidenced by its inclusion in CISA's Known Exploited Vulnerabilities catalog with a remediation deadline of October 7, 2024. The EPSS score of 9.76% (92.8th percentile) indicates significant ongoing exploitation activity. The vulnerability was addressed in Microsoft's September 2024 Patch Tuesday update, and the Microsoft Security Response Center advisory provides detailed patching guidance. The ransomware association is listed as "Unknown" in the KEV catalog. MSHTML vulnerabilities have historically been popular with advanced threat actors because the rendering engine is deeply embedded in Windows and can be triggered through multiple attack vectors beyond web browsing, including email previews, document rendering, and file handling. The spoofing nature of the vulnerability makes it particularly useful in social engineering campaigns where the goal is to deceive the user into taking a harmful action.
Remediation
-
Apply Microsoft's September 2024 security update immediately for all affected Windows versions. Download the appropriate update from the Microsoft Security Response Center or deploy through Windows Update, WSUS, or your enterprise patch management system.
-
Prioritize patching for Windows systems that process external content, including email servers running Outlook, workstations used for web browsing and email, and systems that handle documents from external sources. These systems face the highest exploitation risk due to the user interaction requirement.
-
Configure Windows Defender SmartScreen and Application Guard to provide additional protection against spoofing attacks. SmartScreen can help identify suspicious files and URLs, while Application Guard provides hardware-based isolation for browser sessions on Microsoft Edge.
-
Educate users about the risk of spoofed content, particularly in email attachments and web links. Since this is a spoofing vulnerability, user awareness is an important complementary defense. Train users to verify file extensions, hover over links before clicking, and report suspicious content.
-
Review and restrict MSHTML usage across the organization where possible. Consider disabling Internet Explorer components through Group Policy and configuring registry settings to limit MSHTML's capabilities. For applications that embed MSHTML for HTML rendering, evaluate whether alternative rendering engines can be used.
Technical Details
CVE-2024-43461 has a CVSS v3.1 base score of 8.8 (High) with the vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. The vector analysis shows: Attack Vector (AV:N) confirms the vulnerability is exploitable over the network. Attack Complexity (AC:L) indicates the spoofing attack is straightforward to execute. Privileges Required (PR:N) means no authentication is needed by the attacker. User Interaction (UI:R) is the key requirement — the victim must view or interact with the spoofed content for exploitation to succeed. Scope (S:U) indicates impact remains within the MSHTML/user context. Confidentiality (C:H), Integrity (I:H), and Availability (A:H) are all rated High.
The attack targets the MSHTML platform (Trident engine), which is the HTML rendering engine historically used by Internet Explorer and deeply integrated into Windows. MSHTML is invoked by numerous Windows components and applications for rendering HTML content, including Outlook (email HTML rendering), Windows Search (indexing HTML files), and ActiveX controls. The spoofing vulnerability allows an attacker to craft malicious content that misrepresents its true nature when rendered by MSHTML. This could involve manipulating file extension display, URL presentation, or content type indicators to trick users into executing malicious payloads. The wide scope of affected systems — spanning Windows 10 1507 through Windows 11 24H2 and Windows Server 2008 through 2022 23H2 — reflects MSHTML's fundamental role in the Windows operating system. Even on systems where Internet Explorer is disabled, MSHTML remains active as a system component used by other applications.
Frequently Asked Questions
What is CVE-2024-43461?
CVE-2024-43461 is a spoofing vulnerability in the Windows MSHTML Platform (Trident engine) that allows attackers to manipulate how content is displayed to users. It affects virtually all supported Windows versions and is actively exploited in the wild.
Am I affected even if I don't use Internet Explorer?
Yes. While Internet Explorer is the most well-known user of MSHTML, the rendering engine is deeply integrated into Windows and is used by many applications including Outlook, Windows Search, and third-party software. Disabling Internet Explorer does not remove MSHTML from the system.
How could an attacker exploit this vulnerability?
An attacker could create malicious content that, when rendered by MSHTML, appears different from its true nature. For example, a malicious executable could be presented as a harmless document, or a phishing URL could be displayed as a legitimate website address. The attack requires the user to view or interact with the spoofed content.
Which Windows versions are affected?
Virtually all current Windows versions are affected, including Windows 10 (all supported versions), Windows 11 (21H2 through 24H2), and Windows Server (2008, 2008 R2, 2012, 2012 R2, 2016, 2019, 2022, and 2022 23H2). Check Microsoft's security advisory for specific build numbers that resolve the vulnerability.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.