Today is Microsoft’s October 2024 Patch Tuesday, which includes security updates for 118 flaws, including five publicly disclosed zero-days, two of which are actively exploited.

This Patch Tuesday fixed three critical vulnerabilities, all remote code execution flaws.

The number of bugs in each vulnerability category is listed below:

• 28 Elevation of Privilege vulnerabilities
• 7 Security Feature Bypass vulnerabilities
• 43 Remote Code Execution vulnerabilities
• 6 Information Disclosure vulnerabilities
• 26 Denial of Service vulnerabilities
• 7 Spoofing vulnerabilities

This count does not include three Edge flaws that were previously fixed on October 3rd.

To learn more about the non-security updates released today, you can review our dedicated articles on the new Windows 11 KB5044284 and KB5044285 cumulative updates and the Windows 10 KB5044273 update.

Four zero-days disclosed

This month’s Patch Tuesday fixes five zero-days, two of which were actively exploited in attacks, and all five were publicly disclosed.

Microsoft classifies a zero-day flaw as one that is publicly disclosed or actively exploited while no official fix is available.

The two actively exploited zero-day vulnerabilities in today’s updates are:

CVE-2024-43573 – Windows MSHTML Platform Spoofing Vulnerability

While Microsoft has not shared any detailed information about this bug or how it’s exploited, they did state it involved the MSHTML platform, previously used by Internet Explorer and Legacy Microsoft Edge, whose components are still installed in Windows.

“While Microsoft has announced retirement of the Internet Explorer 11 application on certain platforms and the Microsoft Edge Legacy application is deprecated, the underlying MSHTML, EdgeHTML, and scripting platforms are still supported,” explained Microsoft.

“The MSHTML platform is used by Internet Explorer mode in Microsoft Edge as well as other applications through WebBrowser control. The EdgeHTML platform is used by WebView and some UWP applications. The scripting platforms are used by MSHTML and EdgeHTML but can also be used by other legacy applications.”

While not confirmed, this could be a bypass of a previous vulnerability that abused MSHTML to spoof file extensions in alerts displayed when opening files. A similar MSHTML spoofing flaw was disclosed last month when attacks utilized Braille characters in filenames to spoof PDF files.

Microsoft has not shared who disclosed the vulnerability.

CVE-2024-43572 – Microsoft Management Console Remote Code Execution Vulnerability

This flaw allowed malicious Microsoft Saved Console (MSC) files to perform remote code execution on vulnerable devices.

Microsoft fixed the flaw by preventing untrusted MSC files from being opened.

“The security update will prevent untrusted Microsoft Saved Console (MSC) files from being opened to protect customers against the risks associated with this vulnerability,” explained Microsoft.

It is unknown how this flaw was actively exploited in attacks. 

Microsoft says the bug was disclosed by “Andres and Shady”.

Microsoft says that both of these were also publicly disclosed.

The other three vulnerabilities that were publicly disclosed but not exploited in attacks are:

CVE-2024-6197 – Open Source Curl Remote Code Execution Vulnerability

Microsoft fixed a libcurl remote code execution flaw that could cause commands to be executed when Curl attempts to connect to a malicious server.

“The vulnerable code path can be triggered by a malicious server offering an especially crafted TLS certificate,” explains a Curl security advisory.

Microsoft fixed the flaw by updating the libcurl library used by the Curl executable bundled with Windows.

The flaw was discovered by a security researcher named “z2_,” who shared technical details in a HackerOne report.

CVE-2024-20659 – Windows Hyper-V Security Feature Bypass Vulnerability

Microsoft fixed a UEFI bypass that could allow attackers to compromised the hypervisor and kernel.

“This Hypervisor vulnerability relates to Virtual Machines within a Unified Extensible Firmware Interface (UEFI) host machine,” explains Microsoft.

“On some specific hardware it might be possible to bypass the UEFI, which could lead to the compromise of the hypervisor and the secure kernel.”

Microsoft says that an attacker needs physical access to the device and must reboot it to exploit the flaw.

The flaw was discovered by Francisco Falcón and Iván Arce of Quarkslab but it is not known where it was publicly disclosed.

CVE-2024-43583 – Winlogon Elevation of Privilege Vulnerability

Microsoft fixed an elevation of privileges flaw that could give attackers SYSTEM privileges in Windows.

To be protected from this flaw, Microsoft says that admins must take additional actions.

“To address this vulnerability, ensure that a Microsoft first-party IME is enabled on your device,” explains Microsoft.

“By doing so, you can help protect your device from potential vulnerabilities associated with a third-party (3P) IME during the sign in process.”

Microsoft says wh1tc & Zhiniang Peng of pwnull discovered the flaws.

Recent updates from other companies

Other vendors who released updates or advisories in October 2024 include:

The October 2024 Patch Tuesday Security Updates

Below is the complete list of resolved vulnerabilities in the October 2024 Patch Tuesday updates.

To access the full description of each vulnerability and the systems it affects, you can view the full report here.

Update 9/11/24: Updated to explain that only three flaws were actively exploited and why CVE-2024-43491 was marked as exploited.