CVE-2026-69356

Microsoft Exchange Server Spoofing Vulnerability

CVE-2026-69356 is fixed in 4 products on 1 platform, first by KB5121611, released September 8, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

9.3

Important

Exploitation

None reported

Exploitation Less Likely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0076

55th percentile

<p>Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.</p>

Where it's fixed

Product	Fix	Released
Microsoft
Microsoft Exchange Server 2016 Cumulative Update 23	KB5121611	Sep 8, 2026
Microsoft Exchange Server 2019 Cumulative Update 14	KB5121610	Sep 8, 2026
Microsoft Exchange Server 2019 Cumulative Update 15	KB5121609	Sep 8, 2026
Microsoft Exchange Server Subscription Edition RTM	KB5121608	Sep 8, 2026

Details

Published
September 8, 2026
Weakness
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69356

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