CVE-2026-55018 Microsoft CVE debrief

Who should care

Users of Microsoft Office, particularly those using Microsoft 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024, should be aware of this vulnerability and take necessary precautions. This includes reviewing and applying patches provided by Microsoft, ensuring all Microsoft Office applications are up-to-date, and implementing compensating controls such as monitoring for suspicious activity.

Technical summary

The vulnerability is a use-after-free issue in Microsoft Office, which allows an unauthorized attacker to execute code locally. The CVSS vector is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. The weakness is classified as CWE-416. This issue affects Microsoft Office, particularly Microsoft 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024. Users should ensure their applications are up-to-date and consider implementing compensating controls.

Defensive priority

High

Recommended defensive actions

• Apply the patch provided by Microsoft
• Ensure all Microsoft Office applications are up-to-date
• Implement compensating controls, such as monitoring for suspicious activity
• Conduct regular inventory checks to ensure all systems are patched
• Consider implementing additional security measures, such as network segmentation

Evidence notes

The CVE record was published on 2026-07-14T18:18:12.287Z and was last modified on 2026-07-16T15:22:31.510Z. The NVD entry is currently Analyzed. This vulnerability affects Microsoft Office, particularly Microsoft 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024. Users should verify their deployments and ensure they are up-to-date. The CVE details are sourced from CVE.org and NVD.

Official resources