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CVE-2026-88123 Microsoft CVE debrief

A vulnerability in the DNS Server role of various Windows Server versions allows an authorized attacker to cause a denial of service over a network. The vulnerability is rated with a CVSS score of 6.5 and a severity of MEDIUM. Microsoft has released patches for affected versions. System administrators and security teams should assess exposure, apply patches, and ensure proper security controls are in place to prevent exploitation. The CVE record and source item provide details on the vulnerability, affected versions, and references to vendor advisories and patches. Affected versions include Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, and

Vendor
Microsoft
Product
Windows Server 2012
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-13
Original CVE updated
2026-10-14
Advisory published
2026-10-13
Advisory updated
2026-10-14

Who should care

System administrators and security teams responsible for Windows Server deployments, particularly those using the DNS Server role, should assess exposure and apply patches to prevent denial of service attacks.

Why it matters

The CVE-2026-88123 vulnerability in the DNS Server role of various Windows Server versions allows an authorized attacker to cause a denial of service. System administrators and security teams should assess exposure, apply patches, and ensure proper security controls are in place to prevent exploitation.

  • Verify and apply patches for affected Windows Server versions to prevent exploitation.
  • Assess exposure of DNS Server role deployments and prioritize patching accordingly.
  • Monitor system configurations and ensure proper security controls are in place.

Technical summary

The vulnerability is caused by an out-of-bounds read in the DNS Server role, allowing an authorized attacker to deny service over a network. Affected versions include Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025.

Defensive priority

Apply patches for affected Windows Server versions to prevent denial of service attacks.

Recommended defensive actions

  • Apply patches for affected Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025 versions.
  • Verify affected versions and apply patches accordingly.
  • Review system configurations and ensure DNS Server role is properly secured.

Evidence notes

The CVE record and source item provide details on the vulnerability, affected versions, and references to vendor advisories and patches. The vulnerability is caused by an out-of-bounds read in the DNS Server role, allowing an authorized attacker to deny service over a network. The source item provides details on the vulnerability and affected versions. The CVE Program record and NVD detail page offer additional information on the vulnerability and its severity. Vendor advisories and

Sources and references

Verified primary and authoritative sources

  • CVE-2026-88123 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-88123

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

  • CVE-2026-88123 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-88123

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Role: DNS Server Denial of Service Vulnerability

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/88xxx/CVE-2026-88123.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-88123

    Supplemental source - vendor-advisory, patch

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.