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CVE-2026-45456 Microsoft CVE debrief

CVE-2026-45456 is a HIGH severity vulnerability in Microsoft Office that allows an unauthorized attacker to execute code locally due to a type confusion issue. The vulnerability has a CVSS score of 8.4 and was published on 2026-06-09T17:17:19.790Z. The vulnerability affects various versions of Microsoft Office, including Office 2016, Office 2019, Office 2021, and Office 2024, as well as Microsoft 365 Apps and SharePoint Server.

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
HIGH 8.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-19
Advisory published
2026-06-09
Advisory updated
2026-06-19

Who should care

Administrators and users of Microsoft Office, particularly those using vulnerable versions, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by a type confusion issue in Microsoft Office, which allows an attacker to execute code locally. The vulnerability has been assigned a CVSS score of 8.4, indicating a HIGH severity level.

Defensive priority

HIGH

Recommended defensive actions

  • Apply patches or updates provided by Microsoft to vulnerable versions of Office and SharePoint Server.
  • Use secure coding practices and validate user input to prevent exploitation.

Evidence notes

The vulnerability is documented in the CVE record [cve-org] and the NVD detail page [nvd]. Microsoft has also provided a vendor advisory [ref-4] for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45456 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45456

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-45456 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45456

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental 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.