CVE-2026-88218: Windows DNS Remote Code Execution Vulnerability
CVE-2026-88218 is a remote code execution vulnerability in Windows DNS, rated Important by Microsoft, with a CVSS 3.1 base score of 9.8 (Critical). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. Microsoft released the fix on 10 November 2026 in the November 2026 Patch Tuesday, delivered through 10 security updates (KB5131291, KB5131085, KB5131096, KB5131090 and more). It affects 28 products in 2 product families (ESU, Windows).
Key facts
- CVE ID
- CVE-2026-88218
- Severity
- Critical CVSS 9.8
- Microsoft severity
- Important
- Impact
- Remote Code Execution
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- ESU, Windows
From the November 2026 Patch Tuesday briefing
Windows DNS code execution
Windows DNS has a critical remote code execution vulnerability affecting Windows and ESU. Its network reachability, with no sign-in or user action required, places affected DNS infrastructure in the priority deployment group. Microsoft rates exploitation less likely. The underlying weakness is CWE-415, double free. CVSS: 9.8, vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C.
From the briefing, written by an AI model from PatchaPalooza's data.
CVSS score and vector
Microsoft scores CVE-2026-88218 at 9.8 (temporal 8.5) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Double free in Windows DNS allows an unauthorized attacker to execute code over a network.
Frequently asked questions (Microsoft)
How could an attacker exploit this vulnerability?
Successful exploitation of this vulnerability could allow an attacker the ability to gain remote code execution via an in-network attacker calling arbitrary endpoints.
Affected products (28)
ESU
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1607 for 32-bit Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 1607 for x64-based Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 (Server Core installation) | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 22H2 for 32-bit Systems | ||||
| Windows 10 Version 22H2 for ARM64-based Systems | ||||
| Windows 10 Version 22H2 for x64-based Systems |
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 1809 for x64-based Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 (Server Core installation) | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows Server 2022 | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows Server 2022 (Server Core installation) | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 23H2 for x64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 24H2 for ARM64-based Systems | KB5132061 KB5132043 | Security Update Security Update | 10.0.26100.9974 10.0.26100.9911 | Yes No |
| Windows 11 Version 24H2 for x64-based Systems | KB5132061 KB5132043 | Security Update Security Update | 10.0.26100.9974 10.0.26100.9911 | Yes No |
| Windows 11 Version 25H2 for ARM64-based Systems | KB5132043 | Security Update | 10.0.26200.9911 | No |
| Windows 11 Version 25H2 for x64-based Systems | KB5132043 | Security Update | 10.0.26200.9911 | No |
| Windows 11 Version 26H2 for ARM64-based Systems | KB5132043 | Security Update | 10.0.26300.9911 | No |
| Windows 11 Version 26H2 for x64-based Systems | KB5132043 | Security Update | 10.0.26300.9911 | No |
| Windows Server 2025 | KB5131080 KB5131077 | Security Update Security Hotpatch Update | 10.0.26100.33822 10.0.26100.33730 | Yes No |
| Windows Server 2025 (Server Core installation) | KB5131080 KB5131077 | Security Update Security Hotpatch Update | 10.0.26100.33822 10.0.26100.33730 | Yes No |
| Windows 11 Version 26H1 for ARM64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
| Windows 11 version 26H1 for x64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
Security updates (10)
Acknowledgments
- Anonymous
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |