High September 9, 2026

CVE-2026-78518: Security Advisory

CVE-2026-78518 CVSS 8.8

Who it affects: See the summary below.
What to do: Apply the vendor's update in your next patch window.

CVE-2026-78518 Advisory

Severity: HIGH (CVSS 8.8)
KEV Exploited: No

Affected Product

Microsoft Defender Business

Vulnerability

Out-of-bounds read in Microsoft Office Excel allows remote code execution over a network.

Remediation

Apply security updates from Microsoft. Refer to the official advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78518

Recommendation

Prioritize patching due to HIGH severity rating and network-based attack vector.

Data as of September 9, 2026. Sources: nvd.nist.gov, msrc.microsoft.com. Figures are pulled from public vendor and security data and refreshed automatically.

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