CVE-2026-55040

CriticalCVSS 9.1/10Known exploited (CISA KEV)Last modified Aug 19, 2026

Description

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

Metrics

CVSS 3.1 9.1/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weakness enumeration

CWE-1390

Affected software

VendorProductVersions
MicrosoftMicrosoft SharePoint Enterprise Server 2016>= 16.0.0, < 16.0.5561.1001
MicrosoftMicrosoft SharePoint Server 2019>= 16.0.0, < 16.0.10417.20175
MicrosoftMicrosoft SharePoint Server Subscription Edition>= 16.0.0, < 16.0.19725.20434

References

Timeline

Published
Jul 14, 2026
Last modified
Aug 19, 2026
Added to CISA KEV
Aug 18, 2026
NVD status
Analyzed

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CVE-2026-55040: Critical severity, CVSS 9.1 | Vulnix