CVE-2026-20963
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run SharePoint, fix it now.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by Mar 21, 2026.
Patch status
No official fix confirmed yet
Until a fix ships, follow the vendor's mitigations and CISA's required action, limit exposure of affected systems, and watch this record for a patch.
Description
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
Affected products
| Product | Vendor | Affected versions | Fixed in | Source |
|---|---|---|---|---|
| SharePoint | Microsoft | — | — | KEV |
| SharePoint Server | Microsoft | < 16.0.19127.20442; 2016; 2019 | 16.0.19127.20442 | NVD |
Sources: KEV = CISA Known Exploited Vulnerabilities catalog; NVD = NIST National Vulnerability Database.
Intelligence timeline
Developments from the last 30 days, newest first.
- CVSS scoredUpdateKEV
CVE-2026-20963 scored CVSS 9.8: Microsoft SharePoint, Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
CISA lists this as exploited in the wild. Unpatched SharePoint systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
1 earlier event is available with a subscription. See plans.
Coverage
We have not published a story about this vulnerability yet.