CVE-2026-55035 Microsoft CVE debrief

Who should care

Users of Microsoft Office, particularly those using 365 Apps, Office 2016, Office 2019, Office 2021, Office 2024, and SharePoint Server, should be aware of this vulnerability. IT administrators and security teams responsible for Microsoft Office deployments should prioritize patching and review their environments for potential exposure.

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, Office 2024, and SharePoint Server. Microsoft has provided patches for this vulnerability.

Defensive priority

Medium priority should be given to patching this vulnerability, as it could allow local information disclosure. Defenders should focus on patching affected systems, monitoring for suspicious activity, and implementing compensating controls where necessary.

Recommended defensive actions

• Apply patches provided by Microsoft
• Inventory and update affected Microsoft Office installations
• Monitor for suspicious activity related to Microsoft Office
• Consider compensating controls, such as network segmentation

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. Further investigation and testing are recommended to fully understand the impact of this vulnerability. Evidence is limited to CVE and NVD entries. Defenders should verify patch application, review system logs for suspicious activity, and consider compensating controls for exposed systems.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.