CVE-2026-83869

Analyzed Analyzed - Analysis Complete

Integer Underflow in DNS Server Allows Remote Code Execution

Publication date: 2026-10-13

Last updated on: 2026-10-16

Assigner: Microsoft Corporation

Description

Integer underflow (wrap or wraparound) in DNS Server allows an unauthorized attacker to execute code over a network.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-10-13

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-14

EPSS Evaluated

2026-10-18

NVD

CVE-2026-83869

EUVD

EUVD-2026-99397

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_server_2012	r2
microsoft	windows_server_2012	*
microsoft	windows_10_1607	to 10.0.14393.9612 (exc)
microsoft	windows_10_1607	to 10.0.14393.9612 (exc)
microsoft	windows_10_1809	to 10.0.17763.9376 (exc)
microsoft	windows_10_1809	to 10.0.17763.9376 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7652 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7652 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9711 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9711 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9711 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9711 (exc)
microsoft	windows_11_26h1	to 10.0.28000.3231 (exc)
microsoft	windows_11_26h1	to 10.0.28000.3231 (exc)
microsoft	windows_11_26h2	to 10.0.26300.9711 (exc)
microsoft	windows_11_26h2	to 10.0.26300.9711 (exc)
microsoft	windows_server_2016	to 10.0.14393.9612 (exc)
microsoft	windows_server_2019	to 10.0.17763.9376 (exc)
microsoft	windows_server_2025	to 10.0.26100.33650 (exc)
microsoft	windows_server_2022	to 10.0.20348.5761 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-191	The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer underflow (wrap or wraparound) in a DNS Server. It allows an unauthorized attacker to execute arbitrary code over a network without needing authentication or user interaction.

Detection Guidance

Detecting this vulnerability requires monitoring DNS server logs for unusual activity or crashes. Check for DNS server service failures or unexpected network traffic patterns. Use Windows Event Viewer to inspect DNS server logs for errors related to integer underflow or code execution attempts.

Impact Analysis

An attacker could exploit this to run malicious code on affected systems, potentially leading to full system compromise, data theft, or further network infiltration. The high CVSS score indicates severe impact.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the DNS Server component.
Disable the DNS Server service if not in use or restrict network access to it.
Monitor network traffic for suspicious DNS queries or responses that may indicate exploitation attempts.

Hi! I’m here to help you understand CVE-2026-83869. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70