CVE-2026-20963 | Microsoft SharePoint Remote Code Execution Vulnerability

Exp

Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

Published: 2026-01-13 Last update: 2026-04-01 Assigner: [email protected] Source: [email protected]

NVD Status：Analyzed，CVE State: published

View at NVD, CVE.org, EUVD

Threat Intelligence & Risk Assessment for CVE-2026-20963

KEV EPSS CVSS CWE Affected

Conclusion & alert: CVE-2026-20963 is rated Critical Active Threat (94.6/100): CVSS Critical severity, with high exploitation likelihood (EPSS 5.29%, 90th percentile). Core evidence: CISA KEV confirms active exploitation (added 2026-03-18) affecting Microsoft / SharePoint. a weakness (CWE-502) Unauthenticated remote administrative access may be possible. Mandatory action: The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2026-20963

Name: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability · CISA KEV detail

Exploit added: 2026-03-18

Action due: 2026-03-21

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.

Exploit prediction scoring system (EPSS) score for CVE-2026-20963

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-30	6.47%	5.29%	-1.18%
2	2026-05-27	6.09%	6.47%	+0.38%
3	2026-05-26	—	6.09%	—

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-20963

CVSS metrics for this CVE.

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]

Weakness enumeration for CVE-2026-20963

CWE-502 MITRE ↗

Affected software / configurations for CVE-2026-20963

Vendor	Product	Version	Raw CPE
microsoft	sharepoint_server	< 16.0.19127.20442	cpe:2.3:a:microsoft:sharepoint_server:::::subscription:::*
microsoft	sharepoint_server	2016	cpe:2.3:a:microsoft:sharepoint_server:2016::::enterprise:::
microsoft	sharepoint_server	2019	cpe:2.3:a:microsoft:sharepoint_server:2019:::::::*

References for CVE-2026-20963

URL	Tags
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963	Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963	US Government Resource

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