Windows Server DHCP: Out-of-bounds read leads to denial of service
Summary
Microsoft Windows Server DHCP role contains an out-of-bounds read (CWE-125). An authorized attacker with network access can crash or disrupt the DHCP service, causing an outage for clients on the affected network. The CVSS 3.1 base score is 5.3 (Medium), with high attack complexity and low privileges required. Confidentiality and integrity are not affected.
Affected
- Windows Server 2016 and Server Core installation: 10.0.14393.0 before 10.0.14393.9688
- Windows Server 2019 and Server Core installation: 10.0.17763.0 before 10.0.17763.9487
- Windows Server 2022: 10.0.20348.0 before 10.0.20348.5870
- Windows Server 2025 and Server Core installation: 10.0.26100.0 before 10.0.26100.33822 (listed by a third-party aggregator, not verified against Microsoft)
Fixed in
- Security update from the November 2026 Patch Tuesday for the affected Windows Server versions. Verify the build numbers on the MSRC page before rollout.
- Associated KB for Server 2022: KB5131090 (not verified against the Microsoft catalogue).
Workaround
- Unknown. No CVE-specific workaround found. Patching is the only documented fix.
- General practice, not sourced: limit which hosts can reach the DHCP service and keep the DHCP role off internet-facing systems.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact partial.
- Not listed in the CISA KEV catalog. No public proof of concept found.
Our recommendation
- Patch affected Windows Server 2016, 2019, 2022 and 2025 systems with the November 2026 security update in the normal monthly cycle, prioritising servers that run DHCP for many clients.
- Check the MSRC page to confirm fixed build numbers, especially for Windows Server 2025.
- Restrict which hosts can reach the DHCP service and keep the DHCP role off internet-facing systems.
- Monitor DHCP service availability for unexpected outages.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Denial of service – 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
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-119890 msrc.microsoft.com
- CVE.org record CVE-2026-119890 www.cve.org
- Strix AI: CVE-2026-119890 www.strix.ai
- Senserva KB 5131090 senserva.com
- Rapid7: Patch Tuesday November 2026 www.rapid7.com
- Anoop C Nair: Microsoft fixes 1235 security vulnerabilities www.anoopcnair.com
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, 18:30.
Original description (NVD)
Out-of-bounds read in Windows DHCP Server allows an authorized attacker to deny service over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
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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