Microsoft Windows RD Gateway: Denial of service due to memory leak
Summary
A missing memory release in the Remote Desktop Gateway service of several Windows client and server versions allows an unauthorized remote attacker to cause a denial of service. No privileges or user interaction are required, and the attack can be carried out over the network. Only availability is affected; confidentiality and integrity are not (CVSS 3.1: 7.5, High). Exploitation is not known, and the vulnerability is not listed in CISA KEV.
Affected
- Windows 10 Version 1607 (x86 and x64): below 10.0.14393.9612
- Windows 10 Version 1809: below 10.0.17763.9376
- Windows Server 2012 (incl. Server Core): below 6.2.9200.26434
- Windows Server 2012 R2 (incl. Server Core): below 6.3.9600.23470
- Windows Server 2016 (incl. Server Core): below 10.0.14393.9612
- Windows Server 2019 (incl. Server Core): below 10.0.17763.9376
- Windows Server 2022: below 10.0.20348.5761
- Windows Server 2025 (incl. Server Core): below 10.0.26100.33650
Fixed in
- Install the October 2026 security update for the affected Windows version, reaching the fixed builds listed under Affected.
- Third-party data lists KB5126646 (Server 2025) and KB5126651 (Windows 10 1809 / Server 2019). KB numbers for other products could not be confirmed.
Workaround
- No vendor workaround known.
- Interim measure: restrict access to RD Gateway to trusted IP ranges with firewall rules (not a vendor mitigation).
- Restart the RD Gateway service after patching so the patched code is loaded.
Exploitation
- Microsoft rates exploit maturity as Unproven and lists Exploited: No.
- No public proof-of-concept code or in-the-wild exploitation known.
- Not listed in CISA KEV.
- CISA SSVC: automatable yes, technical impact partial.
Our recommendation
- Inventory all RD Gateway hosts and their Windows builds.
- Patch affected hosts, starting with internet-facing servers.
- Until patched, limit RD Gateway access to trusted source ranges.
- Restart the RD Gateway service after patching.
- Monitor RD Gateway hosts for availability problems.
- Patch the full October 2026 RD Gateway update set together, as other RD Gateway issues were fixed in the same release.
- Check the lifecycle status of Windows 10 1607 on Microsoft's lifecycle page.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Denial of service – Remote Desktop Gateway Service
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation unlikely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126646, KB5126868, KB5126835, KB5126836
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-70033 msrc.microsoft.com
- NVD mirror on Vulners: CVE-2026-70033 vulners.com
- CNA record mirror on Vulners: CVE-2026-70033 vulners.com
- VulDB entry 418329 vuldb.com
- OpenCVE: CVE-2026-70033 app.opencve.io
- Zero Day Initiative: October 2026 security update review www.zerodayinitiative.com
- CERT/CC Vulnerability Note 491944 (component function) kb.cert.org
- Strix.ai: CVE-2026-70033 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, 19:11.
Original description (NVD)
Missing release of memory after effective lifetime in Remote Desktop Gateway Service allows an unauthorized 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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