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CVE-2026-73009 Microsoft CVE debrief

A use-after-free vulnerability exists in the Windows Secure Socket Tunneling Protocol (SSTP), which could allow an unauthorized attacker to execute code over a network. This CVE was published on 2026-09-08T18:20:29.810Z and was last modified on 2026-09-17T20:05:51.077Z. The vulnerability has a critical CVSS score of 9.8, indicating a high severity level. Defenders responsible for Windows systems, particularly those exposed to the internet, should assess their exposure and prioritize patching vulnerable systems. The CVE record and NVD detail page provide information on the vulnerability, including its CVSS score and vector. Microsoft has also provided a patch and vendor advisory for

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-17
Advisory published
2026-09-08
Advisory updated
2026-09-17

Who should care

Defenders responsible for Windows systems, particularly those exposed to the internet, should assess their exposure and prioritize patching vulnerable systems.

Why it matters

CVE-2026-73009 is a critical use-after-free vulnerability in Windows Secure Socket Tunneling Protocol (SSTP) that could allow remote code execution. Defenders should prioritize patching vulnerable systems and monitor network traffic for suspicious activity.

  • Remote code execution is possible over the network
  • Patching vulnerable systems is a high priority due to the critical CVSS score
  • Verify system configurations and inventory for vulnerable versions
  • Monitor network traffic for suspicious activity

Technical summary

The vulnerability exists in the Windows Secure Socket Tunneling Protocol (SSTP) due to a use-after-free error. This could allow an attacker to execute code over a network. The CVSS score for this vulnerability is 9.8, indicating a critical severity level.

Defensive priority

Defenders should prioritize patching vulnerable systems, particularly those exposed to the internet, as this vulnerability has a critical CVSS score of 9.8 and could lead to remote code execution.

Recommended defensive actions

  • Apply patches from Microsoft for vulnerable Windows systems
  • Restrict access to SSTP services from untrusted networks
  • Monitor network traffic for suspicious activity
  • Verify system configurations and inventory for vulnerable versions

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, including its CVSS score and vector. Microsoft has also provided a patch and vendor advisory for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-73009 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-73009

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

  • CVE-2026-73009 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-73009

    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.