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CVE-2026-55034 Microsoft CVE debrief

Microsoft SharePoint Server Spoofing Vulnerability debrief. This vulnerability allows an authorized attacker to perform spoofing over a network, impacting SharePoint Server. The vulnerability is a cross-site scripting issue due to improper neutralization of input during web page generation. SharePoint administrators and security teams should assess exposure and apply patches. The CVE record and source item provide details on the vulnerability, but limited information is available on exploitation or impact.

Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
CVSS
HIGH 7.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-10-08
Advisory published
2026-07-14
Advisory updated
2026-10-08

Who should care

SharePoint administrators and security teams should assess exposure and apply patches. These teams need to verify patch deployment and SharePoint server configurations. The vulnerability allows an authorized attacker to perform spoofing, requiring verification of patch deployment and SharePoint server configurations. Security teams should monitor for suspicious activity and assess SharePoint server configurations for

Why it matters

The vulnerability allows an authorized attacker to perform spoofing, requiring verification of patch deployment and SharePoint server configurations.

  • Verify patch deployment to prevent spoofing
  • Assess SharePoint server configurations for vulnerability
  • Monitor for suspicious activity

Technical summary

A spoofing vulnerability in Microsoft SharePoint Server allows an authorized attacker to perform spoofing over a network due to improper neutralization of input during web page generation. The vulnerability impacts SharePoint Server, requiring verification of patch deployment and SharePoint server configurations. SharePoint administrators and security teams should assess exposure and apply patches.

Defensive priority

High priority for SharePoint administrators

Recommended defensive actions

  • Review and apply the available patch from Microsoft
  • Verify SharePoint server versions and configurations
  • Monitor for suspicious activity

Evidence notes

The CVE record and source item provide details on the vulnerability, but limited information is available on exploitation or impact. Evidence is limited to CVE Program and NVD records. Defenders should verify patch deployment and SharePoint server configurations. The vulnerability allows an authorized attacker to perform spoofing, requiring verification of patch deployment and SharePoint server configurations.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55034 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55034

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

  • CVE-2026-55034 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55034

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

Supplemental references

  • Microsoft SharePoint Server Spoofing Vulnerability

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/55xxx/CVE-2026-55034.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55034

    Supplemental source - vendor-advisory, patch

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.