Windows Remote Desktop Services: Stack-based buffer overflow allows privilege escalation
Summary
A stack-based buffer overflow in Windows Remote Desktop Services allows a locally authorized attacker to elevate privileges. The attack requires local access and low-privileged credentials and no user interaction. The CVSS score of 7.8 reflects possible full compromise of confidentiality, integrity and availability on the affected host. The vulnerability is not directly reachable from the internet.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9688)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9487)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7846)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7846)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7711)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
- Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9688)
- Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9487)
- Windows Server 2022 (10.0.20348.0 before 10.0.20348.5870)
Note: Based on the CVE record; not yet verified against the MSRC advisory. Windows Server 2012/2012 R2 status unknown.
Fixed in
Install the Microsoft security update for the affected build (fixed builds listed above, first fixed build per product). KB numbers: Unknown.
Workaround
Unknown.
Exploitation
- No exploitation in the wild known at publication.
- No public proof-of-concept known.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- Not listed in CISA KEV at time of research.
Our recommendation
- Install the monthly cumulative security update on all listed Windows and Windows Server systems, prioritising RDS session hosts.
- Restrict who has interactive or Remote Desktop logon rights on RDS hosts.
- Apply least privilege to local accounts and review accounts with local logon.
- Monitor for unusual privilege changes and new SYSTEM-level processes.
- Verify the affected list and KB numbers on the MSRC advisory and recheck for exploitation over the coming days.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Remote Desktop Services
- 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, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-122166 msrc.microsoft.com
- CVE Record CVE-2026-122166 (CVE.org) www.cve.org
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, 03:30.
Original description (NVD)
Stack-based buffer overflow in Windows Remote Desktop Services allows an authorized attacker to elevate privileges locally.
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.