CVE-2021-34501: Microsoft Excel XLS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability
Microsoft Excel Remote Code Execution Vulnerability
Other sources
This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Excel. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of CONTINUEFRT12 records within XLS files. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process.
— ZDI
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 15.0.5363.1000Patch KB5001993 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.10376.20001Patch KB5001973 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.5188.1000Patch KB5001977 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in https://aka.ms/OfficeSecurityReleases - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.51.210711.01 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.5188.100Patch KB5001977
Event History
Frequently Asked Questions
What is CVE-2021-34501?
CVE-2021-34501 is a vulnerability that allows remote attackers to execute arbitrary code on affected installations of Microsoft Excel.
How severe is CVE-2021-34501?
CVE-2021-34501 has a severity score of 8.8, which is considered high.
What software is affected by CVE-2021-34501?
Microsoft Excel 2016, Microsoft Excel 2013, Microsoft Office Online Server, Microsoft 365 Apps for Enterprise, Microsoft Excel 2013 RT, Microsoft Office 2019 for Mac, Microsoft Office 2019 for 32-bit editions, Microsoft Office 2019 for 64-bit editions, and Microsoft 365 Apps for Enterprise (x86) are affected by CVE-2021-34501.
How do I fix CVE-2021-34501 on Microsoft Excel 2016?
To fix CVE-2021-34501 on Microsoft Excel 2016, you can apply the patch provided by Microsoft. Please refer to the following URL for more information: [link](https://www.microsoft.com/downloads/details.aspx?familyid=896cd62a-4be0-4156-9ba1-b5a7e9cf4e3e)
How do I fix CVE-2021-34501 on Microsoft Excel 2013?
To fix CVE-2021-34501 on Microsoft Excel 2013, you can apply the patch provided by Microsoft. Please refer to the following URL for more information: [link](https://www.microsoft.com/downloads/details.aspx?familyid=db0dadc7-f5ad-446c-a614-82f53cd238d4)