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CVE-2026-55126 Microsoft CVE debrief

CVE-2026-55126 is a high-severity vulnerability in Microsoft Office SharePoint, allowing an authorized attacker to perform spoofing over a network. The vulnerability has a CVSS score of 7.3 and is classified as HIGH. Microsoft has provided a patch and vendor advisory for this issue. Affected product deployments should be reviewed, and owners assigned for follow-up. The vulnerability is caused by improper neutralization of input during web page generation, allowing for cross-site scripting (XSS) attacks.

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
2026-07-16
Advisory published
2026-07-14
Advisory updated
2026-07-16

Who should care

Administrators and users of Microsoft Office SharePoint should be aware of this vulnerability and take necessary precautions to prevent exploitation. This includes reviewing the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Affected operator, platform, vulnerability-management, and security-team impact should be considered.

Technical summary

The vulnerability is caused by improper neutralization of input during web page generation, allowing for cross-site scripting (XSS) attacks. An authorized attacker can exploit this vulnerability to perform spoofing over a network. The affected product is Microsoft Office SharePoint. Defensive impact includes applying the patch provided by Microsoft and ensuring that all SharePoint servers are up-to-date.

Defensive priority

High priority should be given to applying the patch provided by Microsoft and ensuring that all SharePoint servers are up-to-date. Additional security measures such as input validation and output encoding should be implemented. Monitoring for suspicious activity is also recommended. Compensating controls for exposed systems should be reviewed while remediation is scheduled and verified.

Recommended defensive actions

  • Apply the patch provided by Microsoft
  • Ensure all SharePoint servers are up-to-date
  • Monitor for suspicious activity
  • Implement additional security measures such as input validation and output encoding

Evidence notes

The CVE record was published on 2026-07-14T18:18:19.063Z and last modified on 2026-07-16T14:24:03.443Z. The NVD entry is currently Analyzed. This information is based on the provided source corpus. Further verification is recommended to ensure accuracy.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-14T18:18:19.063Z and has not been modified since then. The NVD entry is currently Analyzed.