If your organization uses Microsoft SharePoint, this is for you. A critical flaw, CVE-2026-65660, is being exploited in active attacks, and CISA has flagged it as a known exploited vulnerability. No hype—just practical steps you can take now to protect your data and your people.
What happened
Security researchers and government agencies are tracking CVE-2026-65660, a vulnerability in SharePoint that is now being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities (KEV) catalog, signaling the need for urgent patching. Microsoft has released security updates to mitigate the flaw. For more details, see the CISA KEV entry and the SecurityWeek write-up linked below. You can also review Microsoft’s advisory for CVE-2026-65660 at Microsoft Security Update Guide.
- Who’s affected: SharePoint on-premises deployments and SharePoint Online environments depending on configuration.
- What attackers gain: unauthorized access or control of compromised systems, enabling data exposure or lateral movement.
- Where to look: public-facing SharePoint endpoints, admin portals, and any systems with SharePoint components.
Why it matters
Here’s why this matters to different readers:
- Regular users and content creators: your data could be exposed if a SharePoint site is compromised.
- Small businesses: a single vulnerable server can become a stepping stone to your network; downtime hurts cash flow.
- IT-minded readers: this is a classic patch-and-monitor scenario—patch quickly, verify, and monitor for signs of exploitation.
What you can do now: practical steps
- 1. Check exposure – Inventory whether you’re using SharePoint on-prem, or SharePoint Online in Microsoft 365, and identify any unpatched systems. Start with your admin inventory and public endpoints.
- 2. Patch fast – Apply the latest security updates from Microsoft. If you’re in a managed environment, coordinate with your IT provider. See the Microsoft advisory and Microsoft Update Guide for CVE-2026-65660.
- 3. Tighten access – Review external sharing policies, enable Conditional Access, and require MFA for admin accounts. Limit admin access to trusted networks when possible.
- 4. Monitor and verify – Enable auditing on SharePoint sites, watch for unusual file access, and correlate with your endpoint protection alerts. Ensure your EDR/AV is up to date.
- 5. Backups and recovery – Ensure recent, immutable backups exist and test your restore process. A quick restore test can save hours during an incident.
- 6. Plan for ongoing risk – Create a short, playbook-style plan for future patch windows and communication with stakeholders.
Final thought
Staying patched and vigilant is the best defense. Put a patching window on the calendar, review access rules, and share this with your team so everyone knows what to do when a vulnerability goes public.