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CVE-2026-67639 Microsoft CVE debrief

CVE-2026-67639 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. SQL Server administrators and users, especially those with instances exposed to the internet or used by multiple users, should assess exposure and apply patches immediately. The vulnerability affects SQL Server versions 2017, 2019, 2022, and 2025. To prevent potential exploitation, it is essential to apply patches immediately, review and update inventory of SQL Server instances, and monitor SQL Server -

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

SQL Server administrators and users, especially those with instances exposed to the internet or used by multiple users, should assess exposure and apply patches immediately.

Why it matters

CVE-2026-67639 is a high-severity vulnerability in Microsoft SQL Server that allows authorized attackers to execute code over a network. SQL Server administrators and users should assess exposure and apply patches immediately, especially for instances exposed to the internet or used by multiple users.

  • Authorized attackers may execute code over a network, potentially leading to system compromise.
  • SQL Server instances exposed to the internet or used by multiple users are at higher risk.
  • Patches should be applied immediately to prevent potential exploitation.

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. Affected versions of SQL Server include 2017, 2019, 2022, and 2025.

Defensive priority

Apply patches immediately, especially for SQL Server instances exposed to the internet or used by multiple users.

Recommended defensive actions

  • Apply patches immediately, especially for SQL Server instances exposed to the internet or used by multiple users.
  • Review and update inventory of SQL Server instances to ensure all affected versions are patched.
  • Monitor SQL Server logs for potential exploitation attempts.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score and affected versions of SQL Server. Microsoft has released a patch for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-67639 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-67639

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

  • CVE-2026-67639 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-67639

    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.