How severe is CVE-2026-66818?

CVE-2026-66818 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-66818 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-66818?

CVE-2026-66818 primarily affects Microsoft Sql Server 2017. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-66818?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-66818 published?

CVE-2026-66818 was published on 2026-09-08 and last updated on 2026-09-16.

CVE-2026-66818

CVE-2026-66818 is a high-severity vulnerability in Microsoft Sql Server 2017 with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-269.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-269
Affected product: Microsoft Sql Server 2017
Published: 2026-09-08
Last modified: 2026-09-16

Description

Improper privilege management in SQL Server allows an authorized attacker to elevate privileges over a network.

Frequently asked questions

What is CVE-2026-66818?: Improper privilege management in SQL Server allows an authorized attacker to elevate privileges over a network.
How severe is CVE-2026-66818?: CVE-2026-66818 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-66818 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-66818?: CVE-2026-66818 primarily affects Microsoft Sql Server 2017. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-66818?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-66818 published?: CVE-2026-66818 was published on 2026-09-08 and last updated on 2026-09-16.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66818

Affected products (4)

cpe:2.3:a:microsoft:sql_server_2017:*:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:sql_server_2019:*:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:sql_server_2022:*:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:sql_server_2025:*:*:*:*:*:*:x64:*

More vulnerabilities in Microsoft Sql Server 2017

CVE-2026-67631 — Critical (CVSS 9.8): Heap-based buffer overflow in SQL Server allows an unauthorized attacker to execute code over a network.
CVE-2026-54118 — Critical (CVSS 9.8): Deserialization of untrusted data in SQL Server allows an unauthorized attacker to execute code over a network.
CVE-2026-54117 — Critical (CVSS 9.8): Deserialization of untrusted data in SQL Server allows an unauthorized attacker to execute code over a network.
CVE-2026-78442 — High (CVSS 8.8): Heap-based buffer overflow in Windows OLE DB allows an unauthorized attacker to execute code over a network.
CVE-2026-77487 — High (CVSS 8.8): Improper access control in SQL Server allows an authorized attacker to elevate privileges over a network.
CVE-2026-77486 — High (CVSS 8.8): Integer overflow or wraparound in SQL Server allows an unauthorized attacker to execute code over a network.

All CVEs affecting Microsoft Sql Server 2017 →

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