Windows DNS Server Remote Code Execution Vulnerability
Priority MEDIUM 44Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Microsoft.
Summary
Windows DNS Server Remote Code Execution Vulnerability
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.02253 83rd percentileScored 2026-11-07
Fix Fixed Microsoft: 5 updates
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Microsoft | Windows Server 2012 R2 | 6.3.9600.0 to before 6.3.9600.20069 | 6.3.9600.20069 | Patch available | CNA |
| Microsoft | Windows Server 2012 R2 (Server Core installation) | 6.3.9600.0 to before 6.3.9600.20069 | 6.3.9600.20069 | Patch available | CNA |
| Microsoft | Windows Server 2016 | 10.0.14393.0 to before 10.0.14393.4530 | 10.0.14393.4530 | Patch available | CNA |
| Microsoft | Windows Server 2016 (Server Core installation) | 10.0.14393.0 to before 10.0.14393.4530 | 10.0.14393.4530 | Patch available | CNA |
| Microsoft | Windows Server 2019 | 10.0.17763.0 to before 10.0.17763.2061 | 10.0.17763.2061 | Patch available | CNA |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 to before 10.0.17763.2061 | 10.0.17763.2061 | Patch available | CNA |
| Microsoft | Windows Server version 2004 | 10.0.0 to before 10.0.19041.1110 | 10.0.19041.1110 | Patch available | CNA |
| Microsoft | Windows Server version 20H2 | 10.0.0 to before 10.0.19042.1110 | 10.0.19042.1110 | Patch available | CNA |
- Windows Server 2012 R2 VendorMicrosoft Affected 6.3.9600.0 to before 6.3.9600.20069 Fixed in 6.3.9600.20069 Patch available CNA
- Windows Server 2012 R2 (Server Core installation) VendorMicrosoft Affected 6.3.9600.0 to before 6.3.9600.20069 Fixed in 6.3.9600.20069 Patch available CNA
- Windows Server 2016 VendorMicrosoft Affected 10.0.14393.0 to before 10.0.14393.4530 Fixed in 10.0.14393.4530 Patch available CNA
- Windows Server 2016 (Server Core installation) VendorMicrosoft Affected 10.0.14393.0 to before 10.0.14393.4530 Fixed in 10.0.14393.4530 Patch available CNA
- Windows Server 2019 VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.2061 Fixed in 10.0.17763.2061 Patch available CNA
- Windows Server 2019 (Server Core installation) VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.2061 Fixed in 10.0.17763.2061 Patch available CNA
- Windows Server version 2004 VendorMicrosoft Affected 10.0.0 to before 10.0.19041.1110 Fixed in 10.0.19041.1110 Patch available CNA
- Windows Server version 20H2 VendorMicrosoft Affected 10.0.0 to before 10.0.19042.1110 Fixed in 10.0.19042.1110 Patch available CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* | r2 | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:* | 20h2 | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:* | 2004 | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Microsoft |
- cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* Versions r2 Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:* Versions 20h2 Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:* Versions 2004 Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
Remediation
Microsoft 5 updates
- Monthly Rollup
- Windows 8.1 for 32-bit systems 6.3.9600.20069
- Windows 8.1 for x64-based systems 6.3.9600.20069
- Windows RT 8.1 6.3.9600.20069
- Windows Server 2012 R2 6.3.9600.20069
- Windows Server 2012 R2 (Server Core installation) 6.3.9600.20069
- Security Only
- Windows 8.1 for 32-bit systems 6.3.9600.20069
- Windows 8.1 for x64-based systems 6.3.9600.20069
- Windows Server 2012 R2 6.3.9600.20069
- Windows Server 2012 R2 (Server Core installation) 6.3.9600.20069
- Security Update
- Windows 10 Version 1809 for 32-bit Systems 10.0.17763.2061
- Windows 10 Version 1809 for ARM64-based Systems 10.0.17763.2061
- Windows 10 Version 1809 for x64-based Systems 10.0.17763.2061
- Windows Server 2019 10.0.17763.2061
- Windows Server 2019 (Server Core installation) 10.0.17763.2061
Show 2 more Microsoft updates
- Security Update
- Windows 10 Version 1607 for 32-bit Systems 10.0.14393.4530
- Windows 10 Version 1607 for x64-based Systems 10.0.14393.4530
- Windows Server 2016 10.0.14393.4530
- Windows Server 2016 (Server Core installation) 10.0.14393.4530
- Security Update
- Windows 10 Version 2004 for 32-bit Systems 10.0.19041.1110
- Windows 10 Version 2004 for ARM64-based Systems 10.0.19041.1110
- Windows 10 Version 2004 for x64-based Systems 10.0.19041.1110
- Windows 10 Version 20H2 for 32-bit Systems 10.0.19042.1110
- Windows 10 Version 20H2 for ARM64-based Systems 10.0.19042.1110
- Windows 10 Version 21H1 for 32-bit Systems 10.0.19043.1110
- Windows 10 Version 21H1 for ARM64-based Systems 10.0.19043.1110
- Windows 10 Version 21H1 for x64-based Systems 10.0.19043.1110
- Windows Server, version 2004 (Server Core installation) 10.0.19041.1110
- Windows Server, version 20H2 (Server Core Installation) 10.0.19042.1110
Vendor assessments
Microsoft
Microsoft's page for this CVE →
- Impact
- Defense in Depth
- Exploited
- No
- Publicly disclosed
- No
- Exploitability
- Exploitation Less Likely
Timeline
- 2026-10-02 Threatist record created from CVE-2021-34525
- 2026-10-03 Alias added: GHSA-5jx6-vwcr-r4rq
References
More Microsoft Windows Server 2012 vulnerabilities
- TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2020-01431 Netlogon Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2020-01310 Improper input validation in Microsoft Windows Server KEVCVSS 3.1CRITICAL 10.0
- TI-2017-06077 Microsoft Windows XP SP3, Windows XP x64 XP2, Windows Server 2003 SP2, Windows Vista… KEVCVSS 3.1CRITICAL 9.8
- TI-2015-01465 HTTP.sys in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1… KEVCVSS 3.1CRITICAL 9.8
- TI-2020-01009 Improper input validation in Microsoft Windows Server KEVCVSS 3.1CRITICAL 9.0
Sources
- CVE-2021-34525 · CVE Program
- CVE-2021-34525 · NVD
- FIRST EPSS
- GHSA-5jx6-vwcr-r4rq · GitHub Advisory Database · CC BY 4.0
- CVE-2021-34525 · Microsoft Security Update Guide
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences