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CVE-2026-67631 Microsoft CVE debrief

CVE-2026-67631 is a heap-based buffer overflow vulnerability in Microsoft SQL Server that allows an authorized attacker to execute code over a network. The vulnerability has a CVSS score of 8.8 and is considered HIGH severity. Microsoft has released a patch for this vulnerability. Defenders responsible for SQL Server instances, especially those exposed to the internet or used by multiple users, should prioritize patching vulnerable instances to prevent potential code execution, elevation of privileges, and data breaches. The vulnerability is described in the CVE record and NVD vulnerability detail page. Microsoft has released a vendor advisory and patch for this vulnerability.

Vendor
Microsoft
Product
Microsoft SQL Server 2017 (CU 31)
CVSS
HIGH 8.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-15
Advisory published
2026-09-08
Advisory updated
2026-09-15

Who should care

Defenders responsible for SQL Server instances, especially those exposed to the internet or used by multiple users, should prioritize patching vulnerable instances.

Why it matters

CVE-2026-67631 is a high-severity vulnerability in Microsoft SQL Server that allows authorized attackers to execute code over a network. Defenders should prioritize patching vulnerable instances to prevent potential code execution, elevation of privileges, and data breaches.

  • Potential code execution over a network
  • Elevation of privileges for authorized attackers
  • Possible data breaches or unauthorized access

Technical summary

The vulnerability is a heap-based buffer overflow in Microsoft SQL Server that allows an authorized attacker to execute code over a network. The vulnerability has a CVSS score of 8.8 and is considered HIGH severity. This heap-based buffer overflow occurs in the SQL Server's handling of certain network requests, allowing attackers with appropriate access to execute arbitrary code. Microsoft has released a patch for this vulnerability, and defenders should prioritize patching vulnerable SQL Server instances, especially those exposed to the internet or used by users

Defensive priority

Defenders should prioritize patching vulnerable SQL Server instances, especially those exposed to the internet or used by multiple users.

Recommended defensive actions

  • Patch vulnerable SQL Server instances
  • Verify and apply the Microsoft patch
  • Monitor for suspicious activity on SQL Server instances

Evidence notes

The vulnerability is described in the CVE record and NVD vulnerability detail page. Microsoft has released a vendor advisory and patch for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-67631 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-67631

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

  • CVE-2026-67631 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-67631

    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.