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Windows DHCP Server: Elevation of privilege due to missing authentication

CVE-2026-105588Medium 6.4

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Summary

Windows DHCP Server on Windows Server 2016, 2019, 2022 and 2025 (including Server Core) contains a missing authentication check for a critical function. An attacker who already has high privileges (administrator level) on the local system can elevate privileges further. The flaw is not reachable from the network, so the main risk is lateral movement after a compromised admin account or a foothold on a DHCP host.

Affected

  • Windows Server 2016 and 2016 (Server Core installation): 10.0.14393.0 to before 10.0.14393.9688
  • Windows Server 2019 and 2019 (Server Core installation): 10.0.17763.0 to before 10.0.17763.9487
  • Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5870
  • Windows Server 2025 and 2025 (Server Core installation): 10.0.26100.0 to before 10.0.26100.33822

Fixed in

  • Windows Server 2025: KB5131080, OS build 26100.33822 (released 10 Nov 2026; mapping to this CVE from a third-party tracker, verify in MSRC)
  • Windows Server 2022: KB5131090, OS build 20348.5870 (released 10 Nov 2026; no source explicitly ties this KB to this CVE, verify in MSRC)
  • Windows Server 2019: KB5131085, OS build 17763.9487 (released 10 Nov 2026; unverified against MSRC)
  • Windows Server 2016: Unknown. Check the MSRC page for the KB and build.

Workaround

Unknown. No vendor-documented workaround was found; installing the update is the remedy.

Exploitation

  • No exploitation known in the wild (Rapid7 lists exploitation as less likely; a third-party tracker lists it as not exploited).
  • CISA SSVC: exploitation none, not automatable, total technical impact.
  • MSRC temporal vector E:U: exploit code maturity is unproven.
  • No public proof of concept found.

Our recommendation

  • Install the November 2026 cumulative updates on all affected DHCP servers and verify the OS build number afterwards.
  • Confirm the Windows Server 2016 and 2019 KB and build numbers on the MSRC page, as the mapping is not fully verified.
  • Restrict local administrator rights on DHCP servers and monitor admin logons on these hosts.
  • Prioritise the other DHCP Server fixes of the same Patch Tuesday, in particular the remote code execution issues (CVE-2026-88216, CVE-2026-88243), which are more relevant for network exposure.

Information from Microsoft (Patch Tuesday November 2026)

Severity (Microsoft)
Important
Impact
Elevation of privilege – Windows DHCP Server
Status on Patch Tuesday
Neither exploited nor publicly disclosed
Exploitability assessment
Exploitation less likely
Product family
Windows, Windows ESU (Extended Security Updates)
Updates (KB)
KB5131291, KB5131085, KB5131090, KB5131080, KB5131077

Entry in the Microsoft Security Update Guide

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 13:53.

Original description (NVD)

Missing authentication for critical function in Windows DHCP Server allows an authorized attacker to elevate privileges locally.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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