What is CVE-2026-45659?
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Timeline
- 2026-05-22Published to the U.S. National Vulnerability Database (NVD)
- 2026-05-27First covered in a defend.network daily briefing
- 2026-07-01Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
- 2026-07-04CISA federal remediation deadline (BOD 22-01)
- 2026-07-23NVD record last updated
CISA Known Exploited Vulnerability
Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
Affected product
Microsoft SharePoint Server
Remediation Steps
- Apply Microsoft security update for SharePoint Server immediately
- Restrict Internet exposure of on-premises SharePoint Server instances using firewall rules and network segmentation
- Review access logs for indicators of compromise
- Enable enhanced logging and monitoring on affected SharePoint deployments
References
Referenced in our briefings & reports
- Vulnerability Priority Report – Week 4 of July 2026 (July 27 – August 2)
- Vulnerability Priority Report – Week 3 of July 2026 (July 20 – 26)
- Vulnerability Priority Report – Week 2 of July 2026 (July 13 – 19)
- Vulnerability Priority Report – Week 1 of July 2026 (July 6 – 12)
- Vulnerability Priority Report – Week 5 of June 2026 (June 29 – July 5)
- Critical RCEs and credential leaks: Microsoft SharePoint, CISA AWS exposure, MuddyWater espionage (2026-05-27)
Related vulnerabilities
- CVE-2026-50522 – Microsoft SharePoint (same product)
- CVE-2026-58644 – Microsoft SharePoint (same product)
- CVE-2026-65660 – Microsoft SharePoint (same product)
- CVE-2026-55040 – Microsoft SharePoint (same product)
- CVE-2026-56164 – Microsoft SharePoint Server (same product)
- CVE-2026-32201 – Microsoft SharePoint Server (same product)
Browse all tracked CVEs in the defend.network CVE database →
🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.