Security News > 2021 > November > Microsoft Issues Patches for Actively Exploited Excel, Exchange Server 0-Day Bugs

Microsoft has released security updates as part of its monthly Patch Tuesday release cycle to address 55 vulnerabilities across Windows, Azure, Visual Studio, Windows Hyper-V, and Office, including fixes for two actively exploited zero-day flaws in Excel and Exchange Server that could be abused to take control of an affected system.

The most critical of the flaws are CVE-2021-42321 and CVE-2021-42292, each concerning a post-authentication remote code execution flaw in Microsoft Exchange Server and a security bypass vulnerability impacting Microsoft Excel versions 2013-2021 respectively.

The Exchange Server issue is also one of the bugs that was demonstrated at the Tianfu Cup held in China last month.

"Earlier this year, Microsoft alerted that APT Group HAFNIUM was exploiting four zero-day vulnerabilities in the Microsoft Exchange server," said Bharat Jogi, director of vulnerability and threat research at Qualys.

"This evolved into exploits of Exchange server vulnerabilities by DearCry Ransomware - including attacks on infectious disease researchers, law firms, universities, defense contractors, policy think tanks and NGOs. Instances such as these further underscore that Microsoft Exchange servers are high-value targets for hackers looking to penetrate critical networks," Jogi added.

Other important remediations include fixes for multiple remote code execution flaws in Chakra Scripting Engine, Microsoft Defender, Microsoft Virtual Machine Bus, Remote Desktop Client, and on-premises versions of Microsoft Dynamics 365.

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https://thehackernews.com/2021/11/microsoft-issues-patches-for-actively.html