CRITICAL CISA KEV

CVE-2026-55040

CVSS v3

9.1

CRITICAL

EPSS Score

0.7 %

exploit probability

CISA KEV

Yes

known exploited

Exploitation

—

SSVC status

Description

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

CISA Known Exploited Vulnerability

Date Added: 2026-08-18
Patch Due Date: 2026-08-21
Ransomware Use: Unknown

Technical details

CVSS v3 Vector: 3.1
Published: 2026-07-14
Last Modified: 2026-07-15

Frequently asked questions

What is CVE-2026-55040?

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

Is CVE-2026-55040 actively exploited?

Yes. CVE-2026-55040 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-08-21.

What is the CVSS score for CVE-2026-55040?

CVE-2026-55040 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string 3.1.

Is CVE-2026-55040 affecting your environment?

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