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Microsoft Exchange Vulnerability CVE-2026-62911: What Administrators Should Do and How Zscaler Can Help

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Microsoft Exchange Vulnerability CVE-2026-62911: What Administrators Should Do and How Zscaler Can Help

Microsoft's August 2026 Patch Tuesday addressed CVE-2026-62911, a high-severity authentication bypass in Exchange Server 2016, 2019, and Subscription Edition with a CVSS score of 8.0. Shadowserver identified approximately 22,000 unpatched Exchange servers exposed to the internet as of September 1, 2026, with working exploit code already publicly available according to the Netherlands National Cyber Security Centre. The vulnerability allows attackers with basic privileges to read and send email, download attachments, and take over all mailboxes on affected servers.

Why it matters: Exchange administrators must patch immediately or block internet access to Exchange servers; the window between disclosure and exploit automation has narrowed significantly due to frontier artificial intelligence (AI) models that can develop and execute attacks in minutes.

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vulnerabilities

Microsoft Exchange Vulnerability CVE-2026-62911: What Administrators Should Do and How Zscaler Can Help

Microsoft's August 2026 Patch Tuesday addressed CVE-2026-62911, a high-severity authentication bypass in Exchange Server 2016, 2019, and Subscription Edition with a CVSS score of 8.0. Shadowserver identified approximately 22,000 unpatched Exchange servers exposed to the internet as of September 1, 2026, with working exploit code already publicly available according to the Netherlands National Cyber Security Centre. The vulnerability allows attackers with basic privileges to read and send email, download attachments, and take over all mailboxes on affected servers.

Why it matters: Exchange administrators must patch immediately or block internet access to Exchange servers; the window between disclosure and exploit automation has narrowed significantly due to frontier artificial intelligence (AI) models that can develop and execute attacks in minutes.

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