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PatchSiren cyber security CVE debrief

CVE-2026-55022 Microsoft CVE debrief

A high-severity type confusion vulnerability exists in Microsoft Office, tracked as CVE-2026-55022. This vulnerability allows an unauthorized attacker to execute code locally, with a CVSS score of 7.8. The CVE record was published on 2026-07-14T18:18:12.780Z and has not been modified since then. The vulnerability is caused by a type confusion issue in Microsoft Office. An attacker can exploit this vulnerability by providing a specially crafted file that, when opened, can execute arbitrary code on the affected system. The vulnerability affects various versions of Microsoft Office, including Microsoft 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024. System administrators and users of Microsoft Office should apply patches immediately. Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-16
Advisory published
2026-07-14
Advisory updated
2026-07-16

Who should care

System administrators and 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 apply patches immediately.

Technical summary

The vulnerability is caused by a type confusion issue in Microsoft Office. An attacker can exploit this vulnerability by providing a specially crafted file that, when opened, can execute arbitrary code on the affected system. The vulnerability affects various versions of Microsoft Office, including Microsoft 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024.

Defensive priority

High

Recommended defensive actions

  • Apply patches provided by Microsoft
  • Ensure all users have the latest version of Microsoft Office installed
  • Implement compensating controls, such as restricting access to sensitive files and monitoring for suspicious activity
  • Conduct regular inventory checks to ensure all systems are up-to-date and vulnerable systems are identified
  • Consider implementing additional security measures, such as application whitelisting and network segmentation

Evidence notes

The CVE record and NVD detail provide information on the vulnerability, including its CVSS score and affected products. Microsoft has provided a patch for this vulnerability, which should be applied immediately.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-14T18:18:12.780Z and has not been modified since then.