New Microsoft SharePoint Server Critical Vulnerabilities Released
The Canadian Centre for Cyber Security and the US Cybersecurity and Infrastructure Security Agency have released advisories regarding multiple vulnerabilities for versions of Microsoft SharePoint Server, some of which have been observed to be exploited by attackers.
These vulnerabilities may potentially enable:
Unauthorized attackers to perform privilege elevation (CVE-2026-56164)
Unauthorized and authorized attackers to perform Remote Code Execution (RCE) attacks (CVE-2026-58644 and CVE-2026-45659)
Unauthorized attackers to perform spoofing (CVE-2026-32201)
Unauthorized attackers to bypass a security feature (CVE-2026-55040)
To prevent exploitation of these vulnerabilities, ensure that your systems are updated to the following build numbers or greater:
SharePoint Server Subscription Edition: 16.0.19725.20434
SharePoint Server 2019: 16.0.10417.20175
SharePoint Enterprise Server 2016: 16.0.5561.1001
Additionally, see the below table for security update versions in which these vulnerabilities were first patched:
| CVE | SharePoint Enterprise Server 2016 | SharePoint Server 2019 | SharePoint Server Subscription Edition |
|---|---|---|---|
| CVE-2026-56164 | KB5002891 | KB5002883 | KB5002882 |
| CVE-2026-45659 | KB5002868 | KB5002870 | KB5002863 |
| CVE-2026-32201 | KB5002861 | KB5002854 | KB5002853 |
| CVE-2026-58644 | KB5002880 | KB5002874 | KB5002873 |
| CVE-2026-55040 | KB5002891 | KB5002883 | KB5002882 |
For more information on security updates, please see Microsoft's CVE info pages:
CVE-2026-56164 / CVE-2026-45659 / CVE-2026-32201 / CVE-2026-58644 / CVE-2026-55040
It is recommended that you install these patches as soon as possible if you are running an affected version. Fixed software is available via Microsoft update or can be downloaded directly from Microsoft. You should also regularly audit your user permissions to ensure you don't have more than the number of users with contributor or higher permissions needed to minimize the attack surface of these exploits.
General guidance for protecting your environment is available from the Canadian Centre for Cyber Security.
Please also keep in mind that Microsoft SharePoint Enterprise Server 2016 and Server 2019 will become end of life on July 14, 2026; consider upgrading to a supported version ahead of that date.
This article was updated to include CVE-2026-56164, CVE-2026-32201, CVE-2026-58644 and CVE-2026-55040 on July 15, 2026.