TL;DR
['CISA has added CVE-2026-20963, a Microsoft SharePoint deserialization of untrusted data vulnerability, to its Known Exploited Vulnerabilities Catalog due to evidence of exploitation.', 'FCEB agencies are required to remediate this by the specified due date per BOD 22-01. CISA recommends all organizations prioritize m
What happened
['CISA has added a new entry, CVE-2026-20963, to its Known Exploited Vulnerabilities (KEV) Catalog.', 'The addition is due to evidence of exploitation affecting Microsoft SharePoint.', 'CVE-2026-20963 involves deserialization of untrusted data in SharePoint.']
Why it matters for ops
['This vulnerability allows for deserialization of malicious data, providing an entry point for cyberattacks.', 'Exploitation can lead to unauthorized access and control over affected systems.', 'FCEB agencies must remediate within the specified timeframe as per BOD 22-01 directives.']
Mitigation
- Apply security patches provided by Microsoft for CVE-2026-20963.
- Implement strict validation and whitelisting for serialized objects in SharePoint.
- Monitor systems for signs of exploitation and apply timely remediation measures.
Action items
- Review the KEV catalog entry for detailed information on CVE-2026-20963.
- Remediate affected systems to mitigate potential risks as per BOD 22-01 requirements.
- Enhance monitoring and logging of SharePoint activity to detect suspicious behaviors early.
Detection IOCs
- Intrusion attempts targeting Microsoft SharePoint
- Exploitation patterns involving deserialization of untrusted data
- Attempts to leverage CVE-2026-20963