CVE-2021-34501: Microsoft Excel XLS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability

Published Jul 13, 2021
·
Updated

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

19 affected componentsFixes available
Microsoft Excel 2013
Microsoft Excel 2013
Microsoft Office Online Server
Microsoft Excel 2013 RT
Microsoft Office 2019 for 32-bit editions
Microsoft Excel
Microsoft Office 2019 for 64-bit editions
Microsoft 365 Apps for Enterprise
Microsoft 365 Apps for Enterprise
Microsoft 365 Apps
Microsoft Excel=2013-sp1
Microsoft Excel=2013-sp1
Microsoft Excel=2016
Microsoft Office=2019
Microsoft Office Macos=2019
Microsoft Office Online Server
Microsoft Office 2019 for Mac
Microsoft Excel 2016
Microsoft Excel 2016

Event History

Jul 13, 2021
CVE Published
via Microsoft·07:00 AM
Data Sourced
via Microsoft·07:00 AM
DescriptionSeverityWeakness
Jul 14, 2021
CVE Published
via MITRE·05:54 PM
Data Sourced
via MITRE·05:54 PM
DescriptionSeverity
Feb 23, 2025
Advisory Published
via ZDI·10:12 AM
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Frequently Asked Questions

1

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.

2

How severe is CVE-2021-34501?

CVE-2021-34501 has a severity score of 8.8, which is considered high.

3

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.

4

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)

5

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)

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