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PatchSiren cyber security CVE debrief

CVE-2026-45659 Microsoft CVE debrief

Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability. This high-severity issue could allow an attacker to execute arbitrary code on the affected system. Defenders should assess exposure and prioritize patching or mitigations. The vulnerability is known to be exploited in the wild, and CISA has provided guidance for prioritization and forensics triage. Affected product deployments should be identified, and owners assigned for follow-up. Official advisories and CVE records should be reviewed to validate affected scope, severity, and vendor guidance.

Vendor
Microsoft
Product
SharePoint Server
CVSS
HIGH 8.8
CISA KEV
Listed
Original CVE published
2026-07-01
Original CVE updated
2026-07-01
Advisory published
2026-07-01
Advisory updated
2026-07-01

Who should care

Defenders responsible for Microsoft SharePoint Server deployments should assess exposure and prioritize patching or mitigations. This includes operators, platform administrators, vulnerability management teams, and security teams. They should review compensating controls for exposed systems while remediation is scheduled and verified. Monitoring, detection, and logs for exposed assets should be checked for extra The

Why it matters

Defenders should prioritize patching or applying mitigations for the Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability, as it could lead to code execution on affected systems. This vulnerability is known to be exploited in the wild, and CISA has provided guidance for prioritization and forensics triage.

  • Potential code execution on affected systems
  • Required verification of vendor-provided mitigations
  • Need for compliance with CISA’s BOD 26-04 guidance

Technical summary

The Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability is a high-severity issue that could allow an attacker to execute arbitrary code on the affected system. This vulnerability is known to be exploited in the wild. Defenders should prioritize patching or applying mitigations. The CISA Known Exploited Vulnerabilities catalog and CVE Program record indicate a deserialization of untrusted data vulnerability in Microsoft SharePoint Server.

Defensive priority

High

Recommended defensive actions

  • Apply mitigations in accordance with vendor instructions
  • Ensure compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk guidance
  • Follow CISA’s Forensics Triage Requirements

Evidence notes

The CISA Known Exploited Vulnerabilities catalog and CVE Program record indicate a deserialization of untrusted data vulnerability in Microsoft SharePoint Server. The NVD entry is currently not provided.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45659 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45659

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-45659 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45659

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.