cve 2026 70318

CVE-2026-70318 is an Excel information-disclosure vulnerability that Microsoft published on August 11, 2026, as part of its monthly security release. Administrators should ensure Microsoft 365 Apps and supported perpetual Office installations receive the August Office security update through their assigned servicing channel. It is important to verify the resulting Excel build, as a successful Windows cumulative-update deployment does not guarantee Office is covered. The public advisory at publication did not make all operational details clear, so administrators should check the Security Update Guide for specific product and impact information.