Microsoft · SharePoint Server
CVE-2026-45659
Microsoft SharePoint Remote Code Execution Vulnerability
What it is
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
CISA: Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
What to do
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Deadline for US federal agencies: July 4, 2026
More exploited flaws from Microsoft
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Jul 14, 2026 | Missing Authentication for Critical Function | SharePoint Server | Medium 5.3 | 1.0% |
| Apr 14, 2026 | Improper Input Validation | SharePoint Server | Medium 6.5 | 43% |
| Mar 26, 2024 | Code Injection | SharePoint Server | High 7.2 | 85% |
| Jan 10, 2024 | Privilege Escalation | SharePoint Server | Critical 9.8 | >99.9% |
| Oct 13, 2026 | Command Injection | Windows | High 8.8 | 9.8% |
| Sep 25, 2026 | Code Injection | SharePoint | High 8.8 | 8.2% |
| Sep 8, 2026 | Link Following | Windows | High 7.8 | 0.4% |
| Sep 8, 2026 | Heap-Based Buffer Overflow | Windows | High 7.8 | 0.4% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.