CVE-2026-45659 — Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
CVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
CISA Known Exploited Vulnerability (KEV)
| Vendor / project | Microsoft |
| Product | SharePoint Server |
| Date added | 2026-07-01 |
| Due date | 2026-07-04 |
| Ransomware campaign use | Known |
Description
Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
Required action (CISA)
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.
Notes
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-45659
References
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45659
- KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog