CVE-2026-55028 Microsoft CVE debrief

Who should care

Users of Microsoft Office, particularly those using 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024, should be aware of this vulnerability and take steps to patch or mitigate it. IT administrators and security teams responsible for managing Office deployments should review their environments for potential exposure and prioritize patching based on their environment's specific configurations and risk assessments.

Technical summary

The vulnerability is an out-of-bounds read issue in Microsoft Office, which could allow an unauthorized attacker to disclose information locally. The CVSS score is 5.5, and the severity is MEDIUM. The vulnerability affects various versions of Microsoft Office, including 365 Apps, Office 2016, Office 2019, Office 2021, and Office 2024. Users of these versions should prioritize patching to mitigate the risk of local information disclosure.

Defensive priority

Medium priority should be given to patching this vulnerability, as it could allow local information disclosure. However, the actual priority may vary based on the organization's specific risk profile and the presence of other vulnerabilities.

Recommended defensive actions

• Apply patches provided by Microsoft
• Inventory and update vulnerable Microsoft Office versions
• Monitor for suspicious local activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD details provide information on the vulnerability. However, additional information about the vulnerability's impact and exploitation is limited. Defenders should verify Office versions, review system logs for unusual activity, and ensure patches are applied according to Microsoft's guidance. The lack of detailed exploit information limits the ability to assess specific attack vectors, but general defensive measures against information disclosure should be considered.

Official resources