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Microsoft Remote Desktop Client: Remote code execution through use-after-free

CVE-2026-108458High 8.8

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Summary

A use-after-free flaw (CWE-416) in the Remote Desktop Client of several Windows 10, Windows 11 and Windows Server releases allows remote code execution. The flaw is in the client, not the RDP server. An attacker needs no privileges, but the victim must take an action, such as connecting to a malicious or compromised RDP endpoint. CVSS 3.1 base score is 8.8 (High).

Affected

  • Windows 10 Version 1607 (10.0.14393.0 to before 10.0.14393.9612)
  • Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9376)
  • Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7807)
  • Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7807)
  • Windows 11 Version 23H2 (10.0.22631.0 to before 10.0.22631.7652)
  • Windows 11 Version 24H2 (10.0.26100.0 to before 10.0.26100.9711)
  • Windows 11 Version 25H2 (10.0.26200.0 to before 10.0.26200.9711)
  • Windows 11 Version 26H1 (10.0.28000.0 to before 10.0.28000.3231)
  • Windows Server 2012 and 2012 R2, including Server Core (6.2.9200.0 to before 6.2.9200.26434; 6.3.9600.0 to before 6.3.9600.23470)
  • Windows Server 2016, including Server Core (10.0.14393.0 to before 10.0.14393.9612)

Fixed in

  • Install the October 2026 cumulative update for each affected Windows version (vendor build numbers as listed in the affected section).
  • The first fixed build for Windows 10 1607 and Windows Server 2016 is 10.0.14393.9612; the KB number is unknown and must be confirmed on the MSRC page.

Workaround

Unknown. No vendor workaround was found in the sources.

  • General measure, not from a vendor source: limit RDP client connections to trusted servers and do not open .rdp files from untrusted sources.

Exploitation

  • CISA SSVC assessment: exploitation none, not automatable, total technical impact.
  • No public proof of concept found. No exploitation in the wild reported in the sources reviewed.
  • EPSS score 0.00767 (low), per Vulners.

Our recommendation

  • Patch all affected Windows clients and servers with the October 2026 cumulative updates, starting with the Windows 10 1607 and Server 2016 systems.
  • Replace or upgrade Windows 10 1607 systems if they are out of support, since no further patches are expected.
  • Check the Microsoft support lifecycle for your edition and confirm the fixed builds on the MSRC advisory.
  • Restrict RDP client use to trusted servers and monitor for unusual RDP connections.

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 unlikely
Product family
Windows, Windows ESU (Extended Security Updates)
Updates (KB)
KB5127648, KB5126657, KB5126646, KB5126653, KB5126651, KB5126836

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 31 Oct 2026, 19:11.

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:

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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