CVE-2026-20963 Microsoft SharePoint Deserialization of Untrusted Data
An unauthorized attacker can execute arbitrary code remotely via unsafe deserialization in Microsoft SharePoint Server.
- Exploited in the wild
- Since 18 Mar 2026
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20963?
CVE-2026-20963 is a critical unsafe deserialization vulnerability in Microsoft Sharepoint Server, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Weakness: CWE-502
Which versions are affected by CVE-2026-20963?
It affects 1 product.
Products include Microsoft Sharepoint Server.
How do I fix CVE-2026-20963?
No fix has been published for CVE-2026-20963 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 21 Mar 2026.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-20963 being exploited?
Yes. Attackers have exploited CVE-2026-20963 in the wild since at least 18 Mar 2026.
Other vulnerabilities in Microsoft Sharepoint Server
- CVE-2026-50522 Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
- CVE-2026-58644 Microsoft SharePoint Deserialization of Untrusted Data
- CVE-2025-53770 Microsoft SharePoint Deserialization of Untrusted Data
- CVE-2023-29357 Microsoft SharePoint Server Privilege Escalation
- CVE-2026-55040 Microsoft SharePoint Weak Authentication
Sources
Also known as GHSA-5vr8-9cf6-r7px.