Microsoft Remote Desktop Client: Use after free leads to remote code execution
Summary
A use-after-free weakness (CWE-416) in the Microsoft Remote Desktop Client allows an attacker to execute code over the network. User interaction is required, for example connecting to a malicious or spoofed RDP host, and the attack complexity is high. Microsoft rates the vulnerability as Important with a CVSS 3.1 base score of 7.5.
Affected
- Windows 10 Version 1607, 1809, 21H2, 22H2
- Windows 11 Version 23H2, 24H2, 25H2, 26H1, 26H2
- Windows Server 2012, 2012 R2, 2016
- Windows Server 2022: not confirmed in the sources reviewed; check the MSRC page
Fixed in
- Fixed builds are part of Microsoft's October 2026 security updates; check the exact build per product on the MSRC page
- Example from CNA data: Windows 10 Version 1809 build 10.0.17763.9376 or later
- The CNA data contains conflicting entries; use only the MSRC Security Update Guide for version decisions
Workaround
- Unknown. Microsoft does not list a workaround in the sources reviewed.
- Third-party sources suggest temporarily disabling Remote Desktop; this is not confirmed by the vendor.
Exploitation
- Microsoft lists the CVE as not publicly disclosed and not exploited, with exploitation less likely.
- No public proof of concept found; no CISA KEV entry found in searches (CISA not checked directly).
- EPSS below 1 percent (third-party source).
Our recommendation
- Install the October 2026 cumulative updates on all affected clients and servers.
- Verify installed build numbers against the MSRC page.
- Connect only to trusted RDP hosts; restrict outbound RDP to known hosts or use VPNs or jump hosts.
- Monitor for exploitation reports and changes in CISA KEV status.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Remote Desktop Client
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126835, KB5126836, KB5126868, KB5126651, KB5126657, KB5126655
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide (primary) msrc.microsoft.com
- NVD record and CVSS data (OpenCVE mirror) app.opencve.io
- Vulners NVD record (third party) vulners.com
- Vulners CVE list record (third party) vulners.com
- Strix CVE record (third party) www.strix.ai
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 2 Nov 2026, 18:04.
Original description (NVD)
Use after free in Remote Desktop Client allows an unauthorized attacker to execute code 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.
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.