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PatchSiren cyber security CVE debrief

CVE-2026-64916 Microsoft CVE debrief

A spoofing vulnerability exists in Microsoft SharePoint Server. An authorized attacker could perform spoofing over a network. The vulnerability allows an attacker to deceive users into performing unintended actions or revealing sensitive information. Defenders should assess exposure and prioritize patching to prevent exploitation. This vulnerability is particularly concerning for organizations that rely heavily on SharePoint for internal communications and document management. The ability of an authorized attacker to perform spoofing could lead to unauthorized access or data breaches if not properly addressed.

Vendor
Microsoft
Product
Microsoft SharePoint Enterprise Server 2016
CVSS
MEDIUM 4.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-11
Original CVE updated
2026-10-08
Advisory published
2026-08-11
Advisory updated
2026-10-08

Who should care

Defenders responsible for Microsoft SharePoint Server deployments should assess exposure and prioritize patching. This includes IT administrators, security teams, and anyone responsible for maintaining SharePoint environments. Additionally, security teams should monitor for suspicious activity and assess the exposure of SharePoint Server deployments. Prioritizing patching will help prevent exploitation and reduce the

Why it matters

Defenders should prioritize verifying affected SharePoint Server versions and applying vendor patches to prevent exploitation.

  • Verify and apply patches to prevent exploitation
  • Monitor for suspicious activity
  • Assess exposure of SharePoint Server deployments

Technical summary

The vulnerability exists due to improper neutralization of input during web page generation, allowing an authorized attacker to perform spoofing over a network. This occurs when user-supplied input is not properly sanitized, enabling an attacker to inject malicious scripts or HTML. The vulnerability affects Microsoft SharePoint Server, which is a popular platform for collaboration and document management within organizations. Successful exploitation could lead to unauthorized access or data breaches.

Defensive priority

Defenders should prioritize verifying affected SharePoint Server versions and applying vendor patches.

Recommended defensive actions

  • Verify affected SharePoint Server versions
  • Apply vendor patches
  • Monitor for suspicious activity

Evidence notes

The CVE Program and NVD provide official records of the vulnerability. Microsoft has released a patch for the vulnerability. The CVE record was published on 2026-08-11T17:06:44.871Z and has not been modified since then. Additional details can be found in the vendor advisory and patch. The vulnerability has been assessed as having a medium severity score of 4.6. There are no known instances of exploitation in the wild, but defenders should still prioritize patching.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-64916 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-64916

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

  • CVE-2026-64916 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64916

    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/2026/64xxx/CVE-2026-64916.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64916

    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.