Microsoft · Security update · October 2, 2026

KB5129957: October 2026 security update

KB5129957, released October 2, 2026, fixes 1 CVE in Microsoft Exchange Server 2019 Cumulative Update 14. None of them is reported as exploited. Patch Radar priority: Urgent.

Urgent

CVEs closed

None rated Critical

Exploited

None reported

Exploitation more likely

Microsoft's assessment

Highest EPSS

0.0275

86th percentile

Applies to

Product
Microsoft Exchange Server 2019 Cumulative Update 14

CVEs this fix closes

Priority	CVE	Component	Impact	CVSS	EPSS	Exploitation
Urgent	CVE-2026-96940	Microsoft Exchange Server	Elevation of Privilege	8.8	0.0275	More likely

Released the same day

KB5129955
Microsoft Exchange Server Subscription Edition RTM
KB5129956
Microsoft Exchange Server 2019 Cumulative Update 15
KB5129958
Microsoft Exchange Server 2016 Cumulative Update 23

Vendor advisory

https://support.microsoft.com/help/5129957

Our write-up

October 2026 Patch Tuesday: Microsoft Stopped Sorting by Severity

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