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CVE-2026-77481 Microsoft CVE debrief

A heap-based buffer overflow vulnerability exists in Microsoft SQL Server, allowing 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 security teams should assess exposure and apply patches immediately to prevent exploitation. The vulnerability exists due to improper handling of user input, allowing an attacker to execute arbitrary code. It is essential to verify and limit network exposure for SQL Server instances to prevent unauthorized access.

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, security teams, and operators of SQL Server instances should assess exposure and apply patches immediately to prevent exploitation. They should also verify and limit network exposure for SQL Server instances to prevent unauthorized access and monitor for suspicious activity on SQL Server instances to detect potential attacks.

Why it matters

The CVE-2026-77481 vulnerability in Microsoft SQL Server allows an authorized attacker to execute code over a network due to a heap-based buffer overflow. SQL Server administrators and security teams should assess exposure and apply patches immediately. The vulnerability has a CVSS score of 8.8 and is considered HIGH severity.

  • Verify and limit network exposure for SQL Server instances to prevent unauthorized access.
  • Apply patches immediately to prevent exploitation.
  • Monitor for suspicious activity on SQL Server instances to detect potential attacks.

Technical summary

The vulnerability exists in Microsoft SQL Server and allows an authorized attacker to execute code over a network due to a heap-based buffer overflow. The vulnerability has a CVSS score of 8.8 and is considered HIGH severity. The vulnerability is caused by improper validation of user input, allowing an attacker to execute arbitrary code. SQL Server administrators and security teams should assess exposure and apply patches immediately to prevent exploitation.

Defensive priority

Apply patches immediately, especially for SQL Server instances exposed to untrusted networks.

Recommended defensive actions

  • Apply patches immediately, especially for SQL Server instances exposed to untrusted networks.
  • Verify and limit network exposure for SQL Server instances.
  • Monitor for suspicious activity on SQL Server instances.

Evidence notes

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

Sources and references

Verified primary and authoritative sources

  • CVE-2026-77481 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-77481

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

  • CVE-2026-77481 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-77481

    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.