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Windows DHCP Server EUVDEUVD-2026-73567

| CVE-2026-69620 HIGH
Stack-based Buffer Overflow (CWE-121)
2026-09-08 secure@microsoft.com GHSA-mhfc-8mjg-g3f4
8.1
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Gain network access to UDP port 67
  2. Delivery
    Craft malformed DHCP packet exploiting CWE-121
  3. Exploit
    Overflow stack buffer in DHCP server parsing code
  4. Execution
    Bypass stack layout constraints (AC:H)
  5. Impact
    Execute arbitrary code as SYSTEM

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

The Windows DHCP Server role must be installed and actively running on the target host - this role is not enabled by default on any listed Windows version and must be explicitly provisioned by an administrator. UDP port 67 must be reachable from the attacker's network position; DHCP relay agents can extend the attack surface beyond the local subnet. The CVSS AC:H metric indicates that straightforward exploitation requires non-trivial skill: the attacker must craft a packet that precisely overflows the stack buffer to achieve reliable control flow hijack, implying knowledge of target build-specific memory layout or a memory disclosure primitive. No authentication or user interaction is required once network access to the DHCP listener is established. Windows 10 endpoints without the DHCP Server component enabled are not exploitable via this path.

Impact

The CVSS 8.1 score is substantiated by the network-reachable, zero-authentication attack surface of DHCP, but AC:H materially limits real-world exploitability - reliable exploitation almost certainly demands heap/stack layout fingerprinting or a triggered race condition, making opportunistic mass exploitation unlikely at launch. No public exploit code has been identified and this CVE is not listed in the CISA KEV catalog. EPSS data is absent from the provided intelligence, so probabilistic exploitation likelihood cannot be independently assessed. That said, the DHCP Server role is pervasive in enterprise and government Active Directory environments, meaning even a mid-sized municipal IT team in zabrze should treat this as urgent given the service's privileged position and the completeness of the C:H/I:H/A:H impact triad. Compensating controls (firewall isolation, DHCP relay inspection) can reduce exposure for organizations that cannot patch immediately.

Exploit ScenarioDerived

An attacker with network access to a Windows Server running the DHCP Server role sends a specially crafted DHCP DISCOVER or REQUEST packet designed to overflow a fixed stack buffer in the server's packet parsing routine. After satisfying the exploitation complexity (likely requiring knowledge of the target build's stack layout or a reliable heap-spray primitive), the attacker redirects execution to shellcode or a ROP chain, gaining SYSTEM-level code execution on the DHCP server. Because the DHCP Server typically runs as SYSTEM and manages critical network infrastructure, full domain network control is achievable from this initial foothold. No public proof-of-concept code is known at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.7% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 09, 2026

Stack-based buffer overflow in the Windows DHCP Server service enables network-adjacent unauthenticated attackers to achieve remote code execution across a broad range of Windows Server versions, from Server 2012 through Server 2025. The flaw (CWE-121) resides in the DHCP server's packet-processing logic, where a malformed client request can overwrite the stack frame and redirect execution - effectively granting SYSTEM-level code execution on the host. No public exploit code or CISA KEV listing has been identified at time of analysis, but patch availability from Microsoft via the MSRC is confirmed.

RemediationAI

Vendor-released patch is available from Microsoft via the standard Windows Update and WSRC channels. Organizations should apply the following minimum build versions: Windows Server 2012 to 6.2.9200.26349, Windows Server 2012 R2 to 6.3.9600.23397, Windows Server 2016 to 10.0.14393.9512, Windows Server 2019 to 10.0.17763.9245, Windows Server 2022 to 10.0.20348.5622, and Windows Server 2025 to 10.0.26100.33438. Consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69620 for the complete patch guidance. Where immediate patching is not feasible, limit network access to UDP port 67 on DHCP servers to trusted network segments only using host-based or perimeter firewall rules - this does not eliminate the vulnerability but significantly reduces the attacker's reach. Do not rely on DHCP relay inspection alone, as forged DISCOVER packets can originate from within allowed segments.

Affected VersionsENISA

Windows Server 2012 6.2.9200.0 <6.2.9200.26349
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9245
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9512
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23397
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9245
Windows Server 2022 10.0.20348.0 <10.0.20348.5622
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23397
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9512
Windows Server 2016 10.0.14393.0 <10.0.14393.9512
Windows Server 2019 10.0.17763.0 <10.0.17763.9245
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26349
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33438
Windows Server 2025 10.0.26100.0 <10.0.26100.33438

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9512
euvd windows_10_version_1809 fix: 10.0.17763.9245
euvd windows_server_2012 fix: 6.2.9200.26349
euvd windows_server_2012_r2 fix: 6.3.9600.23397
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23397
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26349
euvd windows_server_2016 fix: 10.0.14393.9512
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9512
euvd windows_server_2019 fix: 10.0.17763.9245
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9245
euvd windows_server_2022 fix: 10.0.20348.5622
euvd windows_server_2025 fix: 10.0.26100.33438
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33438

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 13 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The Windows DHCP Server role is a built-in network service that listens on UDP port 67 and processes client DISCOVER, REQUEST, and INFORM messages without requiring prior authentication. CWE-121 (Stack-Based Buffer Overflow) indicates that a crafted DHCP packet triggers a write beyond a fixed-size stack-allocated buffer, allowing an attacker to overwrite the return address or other control-flow data. Affected products span Windows Server 2012 through Windows Server 2025 (including Server Core installations), as well as Windows 10 versions 1607 and 1809 - the latter inclusion likely reflects a shared codebase component rather than end-user DHCP server deployments. The CVSS vector uses AC:H, signaling that exploitation is not trivially automatable and likely requires precise memory layout knowledge, timing, or a specific packet sequence to reliably control the overflow.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 8.1 HIGH

Network-facing DHCP listener requires no auth; AC:H reflects exploitation complexity for reliable stack overflow control; full C/I/A because SYSTEM-level RCE on DHCP host.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch available
Sep 08, 2026 - 18:35 EUVD
CVE Published
Sep 08, 2026 - 18:19 nvd
HIGH 8.1

DescriptionCVE.org

Stack-based buffer overflow in Windows DHCP Server allows an unauthorized attacker to execute code over a network.

Executive ViewAI

Why It Matters

Windows DHCP Server is vulnerable to unauthenticated remote compromise across Server versions 2012-2025, affecting any organization with Windows-based network infrastructure. Successful exploitation grants attackers administrative-level control of affected servers, which frequently serve as domain controllers or reside on critical infrastructure. No public exploit identified at time of analysis, but immediate patching is mandatory given the administrative-level access and broad version coverage.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.7%
Top 48% exploitable
Prevalence
High
Default DHCP service in enterprise Windows Server AD deployments
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Unlikely
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.7%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

41
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +40
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.

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