CVE-2026-20963: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Description quoted from the CVE record (assigned by microsoft, published 2026-01-13).
Weakness: CWE-502: Deserialization of Untrusted Data
How it can be exploited
Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: 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
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.
- On CISA KEV since
- 2026-03-18
- US federal deadline
- 2026-03-21
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-00638, CNNVD-202601-2033, CNVD-2026-07204, EUVD-2026-2114, GHSA-5vr8-9cf6-r7px
Exploit Observer links 1 piece of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (1)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/jenniferreire26/cve-2026-20963
Vulnerability databases and vendor advisories (8)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-2114
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-5vr8-9cf6-r7px
- Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-20963
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-20963
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202601-2033
- Vulnerability database or vendor advisory: https://www.cnvd.org.cn/flaw/show/CNVD-2026-07204
- Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2026-20963
2 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.292
likely to be attacked soon - VEDAS
- 0.583
some exploit evidence - On CISA KEV
- Yes, since 2026-03-18
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Microsoft Microsoft SharePoint Enterprise Server 2016 | from 16.0.0 before 16.0.5535.1001 | Not stated |
| Microsoft Microsoft SharePoint Server 2019 | from 16.0.0 before 16.0.10417.20083 | Not stated |
| Microsoft Microsoft SharePoint Server Subscription Edition | from 16.0.0 before 16.0.19127.20442 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: microsoft sharepoint_server, microsoft_corp microsoft_sharepoint_enterprise_server_2016, microsoft_corp microsoft_sharepoint_server_2019, microsoft_corp microsoft_sharepoint_server_subscription_edition.
How to fix it
Fixed versions stated in the CVE record: 16.0.5535.1001, 16.0.10417.20083, 16.0.19127.20442.
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.
Vendor guidance:
- Microsoft SharePoint Remote Code Execution Vulnerability (vendor-advisory, patch)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Vendor advisories and patches
- Microsoft SharePoint Remote Code Execution Vulnerability (vendor-advisory, patch)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.