Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Microsoft — Microsoft SharePoint Enterprise Server 2016
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
9.8
29.4%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- Published
- Jan 13, 2026
- Modified
- Apr 2, 2026
- Added to KEV
- Mar 18, 2026
- Federal patch due
- Mar 21, 2026
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.
Weakness classification
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2026-20963, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2026-20963 were found at last check. Absence here is not proof no exploit exists - see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2026-20963?
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-20963?
CVE-2026-20963 has a CVSS base score of 9.8 out of 10 (CVSS 3.1).
Is CVE-2026-20963 actively exploited in the wild?
Yes. CVE-2026-20963 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Mar 18, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2026-20963?
29.4% - meaning FIRST.org's EPSS model estimates a 29.4% probability this vulnerability will be exploited in the wild within 30 days (98% percentile among all scored CVEs).
What type of vulnerability is CVE-2026-20963?
CVE-2026-20963 is classified under CWE-502 (CWE-502: Deserialization of Untrusted Data).
Cross-checked against
Impactr finds and proves whether CVE-2026-20963 - or flaws like it - are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.
Join the waitlist