Known exploited vulnerability
CVE-2026-20963
The short answer
CVE-2026-20963 affects Microsoft Microsoft SharePoint Enterprise Server 2016 and is rated critical (CVSS 9.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-03-18: attackers are using it, so patch it first.
What it is
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Weakness: CWE-502.
Severity
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Mar 18, 2026
Federal due date Mar 21, 2026
EPSS, next 30 days
29%
Higher than 98% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected products
Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition. NVD's record lists the exact affected versions.
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963 Vendor Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963 US Government Resource
Questions
Is CVE-2026-20963 being exploited?
Yes. CISA added CVE-2026-20963 to its Known Exploited Vulnerabilities catalog on 2026-03-18, with a federal remediation due date of 2026-03-21.
How do I fix CVE-2026-20963?
CISA's 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.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
Related
Latest CVEs this week
Critical and High CVEs from the last 7 days, with KEV and EPSS.
Exploited vulnerabilities by vendor
Every vendor in CISA's KEV catalog, with its count.
Microsoft exploited vulnerabilities
Everything CISA lists as exploited for Microsoft.
Vulnerability watch
A briefing and a fix pull request when an advisory hits your dependencies.
Know the day a CVE lands in your code
Connect a GitHub repository and ZeusQA checks its dependencies daily, briefs each advisory and opens the fix. Three test runs free, no card.