Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Added to KEV
2026-03-18
Federal due date
2026-03-21
Vendor
Microsoft
Product
SharePoint
EPSS
90.2th percentile (score 0.053, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2026-20963

CISA short description

Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.

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.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.