CVE-2026-78521: Microsoft Office Word Remote Code Execution Vulnerability
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
Other sources
Microsoft Office Word Remote Code Execution Vulnerability
— Microsoft
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 16.0.5569.1000Patch KB5002923 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.14334.20896 - Upgrade
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Fixed in 16.0.17932.20960 - Upgrade
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Fixed in 16.0.20326.20136 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.10417.20204
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
The attack vector is network-based and does not require attacker privileges or prior authentication. Exploitation requires user interaction.
Which Word deployments are listed as affected?
Affected software includes Microsoft Word 2016; Microsoft 365 Apps for Enterprise; Office LTSC 2021 for 32-bit and 64-bit editions; Office LTSC 2024 for 32-bit and 64-bit editions; and Office LTSC for Mac 2021 and 2024.
What is the expected security impact if exploitation succeeds?
The severity vector rates confidentiality, integrity, and availability impacts as high. The vulnerability is rated high severity with a CVSS score of 8.8.