EUVD-2026-56354
GHSA-fh82-hxh6-p67f
Severity by source
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Adjacent vector reflects same-segment DHCP network requirement; PR:N confirmed by 'unauthorized attacker' in description; C:H for memory disclosure; no integrity or availability impact applies.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Integer underflow (wrap or wraparound) in Windows DHCP Server allows an unauthorized attacker to disclose information over an adjacent network.
AnalysisAI
Information disclosure via integer underflow in the Windows DHCP Server service exposes server process memory to unauthenticated attackers on the same network segment, affecting Windows Server 2012 through 2025 and Windows 10 versions 1607 and 1809 where the DHCP Server role is installed. The root cause is a CWE-125 out-of-bounds read triggered when an integer underflows and wraps around, causing DHCP packet-processing code to read memory outside intended bounds and potentially return it in a server response. No public exploit has been identified at time of analysis, and CISA's SSVC framework rates exploitation as none with partial technical impact, indicating contained but real risk requiring timely patching.
Technical ContextAI
The vulnerability affects the Microsoft Windows DHCP Server service - an administrator-installed server role that manages dynamic IP address assignment via the DHCP protocol. The root cause class is CWE-125 (Out-of-bounds Read), precipitated by an integer underflow (wrap or wraparound): a length, offset, or size variable in DHCP packet parsing decrements below its minimum representable value and wraps to a very large unsigned integer, causing a subsequent memory read to access data outside the intended buffer boundary. The out-of-bounds data is then potentially returned to the requester as information disclosure. The attack vector is adjacent network (AV:A), meaning exploitation requires the attacker to share the same Layer 2 broadcast domain or directly routable subnet as the server. Affected product scope spans a wide CPE range: Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025 (including Server Core variants), as well as Windows 10 versions 1607 and 1809, all running build ranges confirmed by ENISA EUVD-2026-56354.
RemediationAI
Apply the Microsoft-released patches via Windows Update, WSUS, or Microsoft Update Catalog to bring affected systems to or above the following fixed build versions: Windows Server 2012 and Server Core to 6.2.9200.26279 or later; Windows Server 2012 R2 and Server Core to 6.3.9600.23337 or later; Windows Server 2016, Server Core, and Windows 10 Version 1607 to 10.0.14393.9418 or later; Windows Server 2019, Server Core, and Windows 10 Version 1809 to 10.0.17763.9115 or later; Windows Server 2022 to 10.0.20348.5499 or later; Windows Server 2025 and Server Core to 10.0.26100.33296 or later. See https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62718 for official patch guidance. As a compensating control where immediate patching is not possible, restrict Layer 2 access to DHCP server network segments using VLAN segmentation or 802.1X port authentication to limit which hosts can reach the DHCP server - note this does not eliminate the vulnerability but reduces the attacker pool to already-authenticated network users. Disabling the DHCP Server role on systems that do not require it is an effective risk-elimination measure with no side effects beyond requiring an alternative IP assignment mechanism.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
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External POC / Exploit Code
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