EUVD-2026-56397
GHSA-7pwv-3vv8-2r9v
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
DNS service is network-exposed with no auth required per Authentication Bypass tag; AC:H reflects the precise timing needed to win the race condition; full C/I/A from code execution.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DNS allows an unauthorized attacker to execute code over a network.
AnalysisAI
Remote code execution in Windows DNS Server allows unauthenticated network attackers to exploit a race condition in concurrent DNS request processing to achieve full system compromise. The flaw spans Windows Server 2016 through 2025 and select Windows 10 builds, targeting the server-side DNS component; the 'Authentication Bypass' tag indicates the race window undermines an internal access control that would otherwise gate execution. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target system to have the Windows DNS Server role actively installed and running - the vulnerability is in the server-side DNS processing logic, not the DNS client stub resolver present on all Windows systems. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 8.1 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H) encodes a meaningful tension: the exploit is unauthenticated and network-initiated with devastating impact, but AC:H constrains it to attackers who can precisely engineer concurrent-request timing - not a single-packet spray. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | The primary fix is to apply Microsoft's security update, targeting the following minimum patched builds: 10.0.14393.9418 for Windows Server 2016 and Windows 10 Version 1607; 10.0.17763.9115 for Windows Server 2019 and Windows 10 Version 1809; 10.0.20348.5499 for Windows Server 2022; and 10.0.26100.33296 for Windows Server 2025. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, query all systems running Windows Server 2016, 2019, 2022, 2025, or affected Windows 10 builds to confirm DNS Server role deployment and obtain specific build numbers from Microsoft's security advisory. …
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External POC / Exploit Code
Leaving vuln.today