CVSS v3
9.1
CRITICAL
EPSS Score
0.7%
exploit probability
CISA KEV
Yes
known exploited
Exploitation
—
SSVC status
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
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 8/21/2026.
CVE-2026-55040 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string 3.1.
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Ranked by exploit probability (EPSS).