ZDI-21-969: Microsoft Excel XLS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability

Published Aug 11, 2021
·
Updated

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.

Affected Software

1 affected component
Microsoft Excel

Event History

Aug 11, 2021
Advisory Published
via ZDI·12:00 AM
Data Sourced
via ZDI·12:00 AM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

What is the severity of ZDI-21-969?

The severity of ZDI-21-969 is critical as it allows remote code execution in Microsoft Excel.

2

How do I fix ZDI-21-969?

To fix ZDI-21-969, users should apply the latest security updates provided by Microsoft for Excel.

3

What software is affected by ZDI-21-969?

ZDI-21-969 specifically affects Microsoft Excel for Mac installations.

4

What type of attack does ZDI-21-969 facilitate?

ZDI-21-969 facilitates remote code execution attacks requiring user interaction, such as opening a malicious file.

5

Is user interaction required to exploit ZDI-21-969?

Yes, user interaction is required as the target must visit a malicious page or open a malicious file for exploitation.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203