Windows DHCP Client: Heap-based buffer overflow leading to privilege escalation
Summary
A heap-based buffer overflow in the Windows DHCP Client allows an unauthorized attacker to elevate privileges. The attacker needs a position on the same local network segment, and no authentication or user interaction is required according to the CVSS vector. The CVSS base score is 8.8 (High), and the vector rates confidentiality, integrity and availability impact as high.
Affected
- Microsoft Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9974
- Microsoft Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9974
- Microsoft Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
- Microsoft Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9974
- Windows 10, Windows 11 23H2 and Windows Server editions: Unknown, not confirmed in the sources. Do not assume they are unaffected.
Fixed in
- Windows 11 24H2: build 10.0.26100.9974 or later (inferred from the CVE record, not confirmed by the MSRC advisory)
- Windows 11 25H2: build 10.0.26200.9974 or later (inferred, not confirmed)
- Windows 11 26H1: build 10.0.28000.3501 or later (inferred, not confirmed)
- Windows 11 26H2: build 10.0.26300.9974 or later (inferred, not confirmed)
- Cumulative update KB numbers: Unknown.
Workaround
Unknown. No Microsoft workaround is described in the available sources.
Exploitation
- CVSS exploit maturity is "unproven" (E:U).
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Not listed in CISA KEV according to a third-party tracker.
- No public proof of concept and no reports of in-the-wild exploitation known as of 10 November 2026.
Our recommendation
- Install the November 2026 Windows security updates on all affected Windows 11 systems as soon as possible.
- Verify the fixed build numbers and check the MSRC advisory for Windows 10 and Server coverage.
- Limit untrusted devices on office LANs, for example by isolating guest and BYOD Wi-Fi, enabling switch port security and DHCP snooping.
- Recheck exploitation status (CISA KEV, MSRC exploitation flags) at the next review.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE record (CNA: Microsoft) www.cve.org
- Security Update Guide entry (linked page, not verified) msrc.microsoft.com
- Third-party tracker (affected versions, KEV status) www.strix.ai
- MSRC advisory CVE-2026-69777 (analogous DHCP Client, adjacency wording) msrc.microsoft.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 10 Nov 2026, 22:45.
Original description (NVD)
Heap-based buffer overflow in Windows DHCP Client allows an unauthorized attacker to elevate privileges over an adjacent 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.