Deserialization in Microsoft Sharepoint Enterprise Server 2016
CVE-2026-20963
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Vulnerability class: Insecure Deserialization
EPSS: 0.294 (98.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Microsoft Sharepoint Enterprise Server 2016 — versions 16.0.0
- Microsoft Sharepoint Server 2019 — versions 16.0.0
- Microsoft Sharepoint Server Subscription Edition — versions 16.0.0
- Microsoft Sharepoint_server — versions 2016, 2019
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
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.
Public proof-of-concept exploits
References
- secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)
Frequently asked questions
- What is CVE-2026-20963?
- CVE-2026-20963 is a critical-severity vulnerability in Microsoft Sharepoint Enterprise Server 2016, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-01-13.
- How severe is CVE-2026-20963?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2026-20963 known to be exploited?
- Yes. CVE-2026-20963 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-03-18), indicating it is being actively exploited. 1 public proof-of-concept repositories are indexed.