ZeroHour

CVE-2026-69485

mass

Use-of-Uninitialized-Resource RCE in Microsoft Windows Remote Desktop Client

CVSS 3.1
8.8 high
EPSS
<1%p58
Published
()
Modified
AI analysis

Microsoft's Windows Remote Desktop Client contains a use-of-uninitialized-resource flaw (CWE-908) that allows an authorized attacker to execute code over a network. Per the CVSS vector (AV:N/AC:L/PR:L/UI:N), exploitation requires the attacker to hold some level of authorization (low privileges) but involves no user interaction and low attack complexity, occurring while the client processes network session data. Successful exploitation yields code execution with high impact on confidentiality, integrity, and availability on the system running the RDP client. Because the Remote Desktop Client ships by default with Windows desktop and server editions, any Windows system used to initiate Remote Desktop connections is potentially affected, though the available data does not specify affected version ranges. There is currently no known exploitation, no public proof-of-concept, the flaw is not in CISA's KEV, and EPSS puts the 30-day exploitation probability at just 0.9%.

What to do: Apply Microsoft's security update for CVE-2026-69485 as soon as it is published (monitor the MSRC advisory and the next Patch Tuesday); no fixed version number is provided in the available data. Until patched, restrict Remote Desktop client use to trusted RDP servers, require VPN or gateway access for RDP traffic, and keep Network Level Authentication enabled on RDP servers. Given the low EPSS score and absence of known exploitation, this can be prioritized within the normal cadence for high-severity Microsoft fixes rather than as an emergency.

Affected
Microsoft Windows Remote Desktop Client
Estimated exposure
masshundreds of millions of Windows endpoints (RDP client is bundled by default with Windows 10/11 and Windows Server) — The Remote Desktop Client is included by default on essentially all Windows 10/11 and Windows Server installations, putting the potential affected population in the hundreds of millions of endpoints, though actual exploitability depends on…

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

Use of uninitialized resource in Remote Desktop Client allows an authorized attacker to execute code over a network.

Weakness
CWE-908
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

In the news

Windows Remote Desktop Client Vulnerability Allows Attackers to Execute Remote Code

Microsoft patched CVE-2026-69485, an 8.8 CVSS RCE flaw in the Windows Remote Desktop Client affecting Windows 10/11 and Server 2016-2025.

Microsoft's September 2026 updates fix CVE-2026-69485, an Important-rated remote code execution vulnerability (CVSS 3.1: 8.8, temporal 7.7) in the Windows Remote Desktop Client caused by use of an uninitialized resource. An authenticated attacker with low privileges could send a specially crafted network request to execute code on an affected server, with no user interaction required. Microsoft says the flaw was not publicly disclosed before patching and rates exploitation as 'Less Likely' with no evidence of active exploitation. Affected products span Windows Server 2016, 2019, 2022 and 2025 and Windows 10 (1607-22H2) and Windows 11 (23H2-26H1), with fixes delivered via KBs including KB5123099, KB5122876 and KB5122882.

Remote Desktop Services Failures on Windows Servers Following September Update

September 2026 Patch Tuesday updates cause Windows Server 2019/2022/2025 RDS sessions to freeze, forcing administrators to roll back.

Cumulative updates KB5122876 (Windows Server 2019), KB5122882 (2022), and KB5122871 (2025) trigger Remote Desktop Services freezes hours after boot, with RDP connections hanging at 'Connecting…' and Event ID 20498 logged. Administrators trace the fault to an apparent deadlock in RDPSERVERBASE!WDLIB_Close during session teardown; only hard resets restore service and the issue recurs. The same September release patched roughly 973 vulnerabilities, including two actively exploited zero-days (CVE-2026-81963, CVE-2026-85880, both in CISA's KEV) and a critical RDS RCE, CVE-2026-69525 (CVSS 9.8). Workarounds include DISM-based removal of the update or an unofficial FeatureManagement registry key disabling the suspected audio-redirection code path; Microsoft has not yet confirmed the bug.