Vulnerabilities
Microsoft SharePoint Server Spoofing Vulnerability (CVE-2026-63516) Acknowledged
Microsoft has acknowledged a spoofing vulnerability in SharePoint Server (CVE-2026-63516). The issue could allow attackers to impersonate legitimate users or services. Defenders should verify if their SharePoint deployments are affected and apply any forthcoming patches or mitigations.
What happened
Microsoft has publicly acknowledged a spoofing vulnerability in SharePoint Server, identified as CVE-2026-63516. The flaw could allow an attacker to forge authentication credentials or impersonate legitimate users or services within a SharePoint environment.
Impact
Systems that run SharePoint Server and have not applied any mitigation may be susceptible to unauthorized access or credential spoofing. The vulnerability could enable attackers to bypass authentication controls, potentially leading to data exfiltration or unauthorized configuration changes.
What to do
- Confirm whether your SharePoint Server instances (2013, 2016, 2019, 2022, or newer) are running and whether they have the latest security updates.
- Check the Microsoft Security Response Center for an official patch or work‑around. Apply any available updates as soon as they are released.
- Implement strict access controls: enforce MFA, limit administrative privileges, and monitor authentication logs for anomalous activity.
- Consider temporarily disabling any features that rely on the affected authentication flow until a patch is available.
Monitoring and Detection
Keep an eye on Microsoft’s advisories and the CVE database for updates. Use SIEM or log‑analysis tools to detect suspicious login patterns or repeated authentication failures that could indicate exploitation attempts.
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