CVE-2026-20963

**CVE-2026-20963: Microsoft SharePoint Remote Code Execution via Unsafe Deserialization** Microsoft SharePoint contains an unsafe deserialization flaw that allows unauthenticated or low-privileged attackers to execute arbitrary code remotely by sending malformed serialized objects to the application. An attacker exploiting this vulnerability gains code execution in the context of the SharePoint service account, potentially leading to lateral movement, data exfiltration, or persistent access within your environment. **Immediate actions:** Apply Microsoft's security patch as soon as it becomes available. If you cannot patch immediately, restrict network access to SharePoint servers using firewall rules and WAF policies, monitor SharePoint logs for suspicious deserialization exceptions, and review recent access logs for indicators of exploitation. Check your environment for any unauthorized code execution or suspicious service account activity.