CVE-2021-27054: Microsoft Excel XLS File Parsing Use-After-Free 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 XLS files. The issue results from the lack of validating the existence of an object prior to performing operations on the object. 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 14.0.7266.5000Patch KB4493214 - Upgrade
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Patch KB4493203 - Upgrade
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Fixed in 15.0.5327.1000Patch KB4493203 - Upgrade
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Fixed in 15.0.5327.1000Patch KB4493239 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 14.0.7266.5000Patch KB4504707 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch KB4493239 - 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 16.0.5134.1000Patch KB4493200 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.5134.1000Patch KB4493233 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 15.0.5327.1000Patch KB4493234 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.10372.20000Patch KB4493229
Event History
Frequently Asked Questions
What is CVE-2021-27054?
CVE-2021-27054 is a vulnerability that allows remote attackers to execute arbitrary code on affected installations of Microsoft Excel.
How severe is CVE-2021-27054?
CVE-2021-27054 has a severity rating of 7.8, which is considered high.
How do I exploit CVE-2021-27054?
To exploit CVE-2021-27054, remote attackers need the target to visit a malicious page or open a malicious file.
Which versions of Microsoft Excel are affected by CVE-2021-27054?
Microsoft Excel versions 2010, 2013, 2016, and Excel included in Microsoft 365 Apps for Enterprise are affected by CVE-2021-27054.
How can I fix CVE-2021-27054?
Apply the necessary security updates provided by Microsoft to fix CVE-2021-27054. Visit the provided links for the latest updates.