Microsoft · SharePoint
CVE-2026-20963
Microsoft SharePoint Remote Code Execution Vulnerability
What it is
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
CISA: Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.
What to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Deadline for US federal agencies: March 21, 2026
More exploited flaws from Microsoft
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Sep 25, 2026 | Code Injection | SharePoint | High 8.8 | 8.2% |
| Aug 18, 2026 | Weak Authentication | SharePoint | Critical 9.1 | 70% |
| Jul 22, 2026 | Deserialization of Untrusted Data Vulnerability | SharePoint | Critical 9.8 | 3.0% |
| Jul 16, 2026 | Deserialization of Untrusted Data | SharePoint | Critical 9.8 | 16% |
| Jul 22, 2025 | Code Injection | SharePoint | High 8.8 | >99.9% |
| Jul 22, 2025 | Improper Authentication | SharePoint | Medium 6.5 | 99.1% |
| Jul 20, 2025 | Deserialization of Untrusted Data | SharePoint | Critical 9.8 | >99.9% |
| Oct 22, 2024 | Deserialization | SharePoint | High 7.2 | 51% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.