Microsoft · Security update · August 11, 2026

KB5121576: August 2026 security update

KB5121576, released August 11, 2026, fixes 7 CVEs in Microsoft Exchange Server 2016 Cumulative Update 23. None of them is reported as exploited. Patch Radar priority: Urgent.

Urgent
CVEs closed
7
1 rated Critical
Exploited
0
None reported
Exploitation more likely
0
Vendor assessment
Highest EPSS
0.0198
80th percentile

Priority of the 7 CVEs

Patch now 0 Urgent 1 High 3 Routine 3

Applies to

CVEs this fix closes

PriorityCVEComponentImpactCVSSEPSSExploitation
Urgent CVE-2026-62911 Microsoft Exchange Server Elevation of Privilege 8.0 0.0069 Exploitation Less Likely
High CVE-2026-62910 Microsoft Exchange Server Elevation of Privilege 7.2 0.0100 Exploitation Less Likely
High CVE-2026-62913 Microsoft Exchange Server Remote Code Execution 8.8 0.0091 Exploitation Less Likely
High CVE-2026-62914 Microsoft Exchange Server Spoofing 7.3 0.0045 Exploitation Less Likely
Routine CVE-2026-62912 Microsoft Exchange Server Denial of Service 6.5 0.0198 Exploitation Less Likely
Routine CVE-2026-65813 Microsoft Exchange Server Elevation of Privilege 6.5 0.0094 Exploitation Less Likely
Routine CVE-2026-62915 Microsoft Exchange Server Security Feature Bypass 6.5 0.0064 Exploitation Less Likely
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