CVE-2026-55040

Microsoft SharePoint Server Security Feature Bypass Vulnerability

State: Published
Severity: 9.1 Critical
Published: Jul 14, 2026
Updated: Nov 1, 2026
Reserved: Jun 16, 2026

Description

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

Scores

CVSS	Score	Vector	Source
3.1	9.1 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-1390 Weak Authentication

Affected Products

Product	Versions
Microsoft SharePoint Enterprise Server 2016Microsoft	16.0.0 to before 16.0.5561.1001Affected
Microsoft SharePoint Server 2019Microsoft	16.0.0 to before 16.0.10417.20175Affected
Microsoft SharePoint Server Subscription EditionMicrosoft	16.0.0 to before 16.0.19725.20434Affected

References

Microsoft SharePoint Server Security Feature Bypass Vulnerabilityvendor-advisorypatch
https://www.rapid7.com/blog/post/ra-microsoft-sharepoint-jwt-token-authentication-bypass-cve-2026-55040/technical-description
https://github.com/sfewer-r7/CVE-2026-55040exploit
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55040government-resource

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