EUVD-2026-56675
GHSA-2hvq-h28x-grj9
Severity by source
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV:A reflects DHCP's broadcast-domain scope; PR:N because DHCP is unauthenticated by protocol design; full C/I/A from heap overflow enabling arbitrary code execution.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows DHCP Server allows an unauthorized attacker to execute code over an adjacent network.
AnalysisAI
Unauthenticated code execution in Windows DHCP Server allows an attacker positioned on an adjacent network segment to trigger a heap-based buffer overflow and achieve full system compromise. The vulnerability spans a wide range of Microsoft server and desktop platforms, from Windows Server 2012 through Windows Server 2025 and select Windows 10 builds, making it broadly relevant in Windows-centric enterprise environments. No public exploit code or CISA KEV listing has been identified at time of analysis, but the low-complexity, zero-interaction exploitation profile and vendor-confirmed patch availability make this a high-priority patching candidate for any organization running Windows DHCP Server.
Technical ContextAI
The vulnerability resides in the Windows DHCP Server service (dhcpssvc.dll / dhcpserver), which processes DHCP protocol messages over UDP ports 67/68 within a Layer 2 broadcast domain. CWE-122 (Heap-based Buffer Overflow) indicates that a crafted DHCP message causes the server to write beyond the bounds of a heap-allocated buffer, corrupting adjacent heap memory. Because the DHCP protocol is inherently unauthenticated - clients send DISCOVER and REQUEST messages before receiving an address - no credential material is required to deliver a malicious packet to the service. Affected builds range from Windows Server 2012 (build 6.2.9200.x) through Windows Server 2025 (build 10.0.26100.x), as well as Windows 10 versions 1607 and 1809, confirming the flaw is present across a decade of platform releases. The CVSS adjacent-network attack vector (AV:A) correctly reflects that DHCP broadcast traffic is constrained to a single broadcast domain, limiting exploitation to attackers with Layer 2 adjacency or the ability to inject DHCP traffic (e.g., via a rogue relay agent on a routed network).
RemediationAI
The primary remediation is to apply the vendor-released security update via Windows Update or WSUS, targeting the specific fixed builds documented in the EUVD: Windows Server 2025 10.0.26100.33296 or later, Windows Server 2022 10.0.20348.5499 or later, Windows Server 2019 10.0.17763.9115 or later, Windows Server 2016 10.0.14393.9418 or later, Windows Server 2012 R2 6.3.9600.23337 or later, and Windows Server 2012 6.2.9200.26279 or later. The advisory is located at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62823. Where immediate patching is not feasible, compensating controls include: disabling the Windows DHCP Server service on hosts where it is not strictly required (note: this will disrupt DHCP lease assignment for dependent clients); restricting Layer 2 access to the DHCP server port (UDP 67) at the switch level using DHCP snooping, which limits which ports can originate DHCP server traffic (trade-off: adds switch management overhead and may interfere with legitimate relay configurations); and isolating the DHCP server onto a dedicated management VLAN reachable only from trusted infrastructure - this reduces the pool of potential adjacent attackers without impacting service functionality. Note that Windows Server 2012 and 2012 R2 are past mainstream end-of-life; organizations relying on Extended Security Updates should verify ESU patch applicability with Microsoft.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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