CVE-2026-56164
Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
Microsoft SharePoint Server
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 14 July 2026. US federal agencies were required to remediate it by 17 July 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 22.4%, which is higher than 97.5% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Frequently asked questions
Is CVE-2026-56164 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-56164.
What does CVE-2026-56164 affect?
CVE-2026-56164 affects Microsoft SharePoint Server. Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
How severe is CVE-2026-56164?
CVE-2026-56164 is rated MEDIUM with a CVSS base score of 5.3. EPSS puts the probability of exploitation in the next 30 days at 22.4%, higher than 97.5% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 17 July 2026.
How should organisations respond to CVE-2026-56164?
Apply the vendor patch for Microsoft SharePoint Server as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.