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[CVSS 9+] Critical CVE Updates for Microsoft Products

Executive Summary

Microsoft has recently released patches associated with the two open-source software security vulnerabilities actively exploited, CVE-2023-4863 and CVE-2023-5217. Both vulnerabilities have a CVSS of 8.8 and impact Chromium-based browsers. They have been fixed by Google earlier.

CVE-2023-29357 is a critical vulnerability in Microsoft SharePoint Server, allowing privilege escalation. It has a CVSS of 9.8. Microsoft has already fixed it in June. A proof-of-concept exploit for has recently been released on GitHub, although it does not grant remote code execution.

Organizations using impacted Microsoft products are strongly advised to update them.

For further information about the vulnerabilities, please see below.

About CVE-2023-4863

CVE-2023-4863, with a CVSS of 8.8, is a critical heap buffer overflow that resides in the open-source libwebp library used by Chromium-based browsers.

Its exploitation could lead to crashes and remote code execution. On September 11th, Google has rolled out emergency security updates to fix this zero-day vulnerability that has been actively exploited in attacks since the start of 2023.

Microsoft has indicated in their security updates that the following Microsoft products are impacted by this vulnerability:

  • Microsoft Edge
  • Microsoft Teams for Desktop
  • Skype for Desktop
  • Webp Image Extensions (Released on Windows and updates through Microsoft Store)

Please refer to our earlier news regarding CVE-2023-4863 for additional information: [CVSS 9+] Vulnerabilities in Chrome

About CVE-2023-5217

CVE-2023-5217, with a CVSS of 8.8, is a high-severity vulnerability in the VP8 compression format supported by various Chromium-based browsers. This vulnerability was actively exploited and was patched by Google on September 27th.

Microsoft has stated in their security updates that Microsoft Edge is affected by this vulnerability.

For more information, please refer to our earlier news regarding CVE-2023-5217: [Zero-day] Update Chrome now!

About CVE-2023-29357

CVE-2023-29357, with a CVSS of 9.8, can let unauthenticated attackers gain administrator privileges following successful exploitation in low-complexity attacks that don’t require user interaction.

“An attacker who has gained access to spoofed JWT authentication tokens can use them to execute a network attack which bypasses authentication and allows them to gain access to the privileges of an authenticated user”

Microsoft explained in June when they patched the vulnerability.

On September 25, STAR Labs researcher Nguen Tien Giang published a technical analysis detailing the exploitation process for a chain of vulnerabilities. Shortly after the public release of the technical analysis, a proof-of-concept (PoC) exploit was made available on GitHub.

“The script outputs details of admin users with elevated privileges and can operate in both single and mass exploit modes. However, to maintain an ethical stance, this script does not contain functionalities to perform RCE and is meant solely for educational purposes and lawful and authorized testing.”

the exploit’s developer says.

Considering the criticality of the vulnerability and the availability of the exploit PoC on GitHub, it is strongly recommended to prioritize updating SharePoint, even if the PoC does not include RCE (Remote Code Execution).

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