CVE-2026-20963

high

Description

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

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963

https://www.theregister.com/2026/03/19/unknown_attackers_exploit_yet_another/

https://www.securityweek.com/cisa-warns-of-attacks-exploiting-recent-sharepoint-vulnerability/

https://www.helpnetsecurity.com/2026/03/19/sharepoint-vulnerability-cve-2026-20963-exploited/

https://www.bleepingcomputer.com/news/microsoft/critical-microsoft-sharepoint-flaw-now-exploited-in-attacks/

https://thehackernews.com/2026/03/cisa-warns-of-zimbra-sharepoint-flaw.html

https://www.cisa.gov/news-events/alerts/2026/03/18/cisa-adds-one-known-exploited-vulnerability-catalog-0

https://securityaffairs.com/189628/security/u-s-cisa-adds-microsoft-sharepoint-and-zimbra-flaws-to-its-known-exploited-vulnerabilities-catalog.html

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963

Details

Source: Mitre, NVD

Published: 2026-01-13

Updated: 2026-04-01

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.00503

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Interest