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CVE-2026-55135 Microsoft CVE debrief

CVE-2026-55135 is a cross-site scripting vulnerability in Microsoft Office SharePoint. An authorized attacker can perform spoofing over a network. This vulnerability is caused by improper neutralization of input during web page generation. Microsoft Office SharePoint users and administrators should be aware of this vulnerability and review official advisories for mitigation guidance. The vulnerability's impact is currently assessed as medium severity, but further verification is needed to confirm the affected scope and severity.

Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
CVSS
MEDIUM 4.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-16
Advisory published
2026-07-14
Advisory updated
2026-07-16

Who should care

Microsoft Office SharePoint users and administrators should be aware of this vulnerability and review official advisories for mitigation guidance. They should verify their deployments and assess their exposure to this vulnerability. Security teams and vulnerability management teams should also be aware of this vulnerability and prioritize mitigation efforts accordingly.

Technical summary

The vulnerability is caused by improper neutralization of input during web page generation in Microsoft Office SharePoint. An authorized attacker can exploit this vulnerability to perform spoofing over a network. The vulnerability's technical impact is currently assessed as medium severity, but further verification is needed to confirm the affected scope and severity. Defenders should review official advisories and verify their deployments to mitigate this vulnerability.

Defensive priority

Medium priority due to the CVSS score of 4.6.

Recommended defensive actions

  • Apply the patch provided by Microsoft.
  • Review and update SharePoint Server configurations.
  • Monitor for suspicious activity.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record was published on 2026-07-14T18:18:20.307Z and was last modified on 2026-07-16T15:16:33.090Z. The source details are limited, and further verification is needed to confirm the affected scope and severity. Microsoft Office SharePoint users and administrators should verify their deployments and review official advisories for mitigation guidance. The CVE record provides limited information on the vulnerability's impact, and defenders should exercise caution when assessing their exposure.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55135 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55135

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

  • CVE-2026-55135 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55135

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

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.