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Remote Desktop Client CVE-2026-69988

| EUVDEUVD-2026-99846 HIGH
Use After Free (CWE-416)
2026-10-13 secure@microsoft.com GHSA-3942-r52h-9r9g
7.5
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Lure user to malicious RDP server
  2. Delivery
    Client initiates RDP connection
  3. Exploit
    Server sends crafted response
  4. Execution
    Trigger use-after-free in client
  5. Impact
    Execute arbitrary code in user context

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the victim to actively initiate an RDP session from the Windows Remote Desktop Client to a server the attacker controls or can manipulate (UI:R) - the client must connect outward; this is not a flaw in the RDP listener/host and cannot be triggered by an unsolicited inbound connection to the victim. The high attack complexity (AC:H) indicates the use-after-free depends on winning a memory-state race or precise heap conditions rather than a deterministic single-shot trigger. No authentication is required of the attacker (PR:N), and exploitation yields code execution confined to the connecting user's context (S:U). Primary limiting factors defenders can rely on: mandatory user interaction to connect to a hostile endpoint, high exploitation complexity, and the absence of any observed exploitation (SSVC Exploitation=none, no KEV).

Impact

This is a client-side remote code execution flaw (CWE-416 use-after-free) in the Windows Remote Desktop Client, rated CVSS 7.5. The CVSS vector (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H) shows that although the attack is network-reachable and requires no privileges, it carries HIGH attack complexity and REQUIRES user interaction - the victim must be lured into initiating an RDP connection to an attacker-controlled or malicious server. These two limiters (AC:H + UI:R) are why the score lands at 7.5 rather than 9.8 despite total C/I/A impact. The signals are internally consistent and point toward LOWER real-world urgency than the 'RCE' label alone suggests: CISA's SSVC decision framework lists Exploitation=none and Automatable=no (consistent with the user-interaction requirement and high complexity), even though Technical Impact=total. There is no CISA KEV listing and no public exploit identified, so there is no evidence of active or at-scale exploitation. EPSS was not provided in the input, so exploitation probability cannot be quantified here. Net assessment: a genuinely impactful but NON-wormable, interaction-dependent client bug - important to patch on a normal cycle given the ubiquity of the RDP client, but not an emergency 'drop everything' issue absent any exploitation signal.

Exploit ScenarioDerived

An attacker stands up a malicious RDP endpoint (or compromises/spoofs a legitimate one) and uses social engineering - a phishing link, .rdp attachment, or rogue gateway - to induce a user to connect with the Windows Remote Desktop Client. During the session the malicious server returns crafted data that triggers the use-after-free in the client, letting the attacker execute code in the victim's context. No public proof-of-concept was identified at time of analysis, and the high attack complexity (AC:H) means reliable triggering of the freed-memory condition is non-trivial.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.6% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 14, 2026

Remote code execution affects the Windows Remote Desktop Client (mstsc) across a wide range of supported desktop and server builds, allowing an attacker who controls or manipulates an RDP endpoint to execute code in the context of the connecting user. The flaw is a use-after-free (CWE-416) rated CVSS 7.5; exploitation requires the victim to actively initiate an RDP session outward to the hostile server (UI:R), and high attack complexity (AC:H) reflects dependence on heap/race conditions rather than a deterministic trigger - no authentication is required of the attacker (PR:N). No public exploit code has been identified at time of analysis and CISA's SSVC records Exploitation=none with no KEV listing, so risk is driven by the breadth of affected Windows builds and the total technical impact should the memory-corruption primitive be reliably converted into code execution.

RemediationAI

Vendor-released patch: apply the Microsoft cumulative updates that raise affected builds to or above the fixed thresholds - Windows 10 1607 / Server 2016 to 10.0.14393.9612, Windows 10 1809 / Server 2019 to 10.0.17763.9376, Windows 10 21H2 to 10.0.19044.7807 and Windows 10 22H2 to 10.0.19045.7807, Windows 11 23H2 to 10.0.22631.7652, Windows 11 24H2 and Server 2025 to 10.0.26100.9711 (Server 2025 to 10.0.26100.33650), Windows 11 25H2 to 10.0.26200.9711, Windows 11 26H1 to 10.0.28000.3231, Windows 11 26H2 to 10.0.26300.9711, Server 2022 to 10.0.20348.5761, Server 2012 to 6.2.9200.26434 and Server 2012 R2 to 6.3.9600.23470 - with details and download links in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69988. Because this is a client-side flaw that only triggers when a user connects outward to a hostile or compromised RDP endpoint, effective interim mitigations are: block outbound TCP/UDP 3389 from client and administrator workstations to untrusted internet destinations at the egress firewall (lowers exposure where outbound RDP is legitimate, but may disrupt legitimate remote administration and should be scoped to a managed allowlist of approved RDP gateways); prohibit opening .rdp connection files or RDP hyperlinks supplied by untrusted parties via email, chat, or the web, and remove the Remote Desktop Connection client from non-administrative endpoints where it is not operationally required (uninstalling or disabling the component removes the attack surface but disables legitimate remote support workflows); and, where remote access is required, force connections through a brokered RD Gateway or jump host whose endpoints are trusted and patched, since the flaw is not in the RDP listener and cannot be triggered by unsolicited inbound connections to the victim. Prioritize patching for users who routinely initiate RDP sessions to third-party or externally hosted servers, as that population carries the highest residual exposure until the cumulative updates are deployed; note that SSVC rates Automatable=no and Exploitation=none, so emergency out-of-band action is not indicated, but the technical impact rating is total once a working memory-corruption chain is developed.

Affected VersionsENISA

Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26434
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23470
Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
Windows Server 2012 6.2.9200.0 <6.2.9200.26434
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23470
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows Server 2016 10.0.14393.0 <10.0.14393.9612
Windows Server 2025 10.0.26100.0 <10.0.26100.33650

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9612
euvd windows_10_version_1809 fix: 10.0.17763.9376
euvd windows_10_version_21h2 fix: 10.0.19044.7807
euvd windows_10_version_22h2 fix: 10.0.19044.7807
euvd windows_11_version_23h2 fix: 10.0.22631.7652
euvd windows_11_version_24h2 fix: 10.0.26100.9711
euvd windows_11_version_25h2 fix: 10.0.26200.9711
euvd windows_11_version_26h1 fix: 10.0.28000.3231
euvd windows_11_version_26h2 fix: 10.0.26300.9711
euvd windows_server_2012 fix: 6.2.9200.26434
euvd windows_server_2012_r2 fix: 6.3.9600.23470
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23470
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26434
euvd windows_server_2016 fix: 10.0.14393.9612
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9612
euvd windows_server_2019 fix: 10.0.17763.9376
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9376
euvd windows_server_2022 fix: 10.0.20348.5761
euvd windows_server_2025 fix: 10.0.26100.33650
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33650

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 20 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is a use-after-free (CWE-416) in the Windows Remote Desktop Client, the client-side component (mstsc.exe and its RDP protocol stack) that renders and drives connections to RDP servers. Because the defect sits in the client, the attack surface is the parsing and teardown of data received from a remote RDP peer during a session the user initiates - malformed or state-manipulating server responses cause a heap object to be freed while a pointer to it remains in use, leading to memory corruption that can be steered toward code execution. The CVSS vector AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H confirms network reachability with no attacker credentials, a mandatory user action (the outbound RDP connection), high complexity consistent with winning a memory-state race or arranging specific heap layout, and impact confined to the connecting user's security context (S:U) rather than crossing a privilege boundary. Per EUVD, every mainstream Windows client and server branch that ships the RDP client is in scope, including Windows 10 1607/1809/21H2/22H2, Windows 11 23H2 through 26H2, and Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025 (including Server Core installations). The affected-version data is expressed as build thresholds (for example 10.0.17763.0 < 10.0.17763.9376 for the 1809/Server 2019 branch), which map to Microsoft's cumulative update servicing baseline; no CPE strings were supplied, so exact component identification should be taken from the vendor's update guide rather than inferred. Tags classify the underlying defect as memory corruption manifesting as use-after-free with denial-of-service potential, while the CVSS confidentiality, integrity, and availability ratings are all High.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.5 HIGH
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 7.5 HIGH

Network-reachable but client-side: victim must connect to a malicious RDP server (UI:R) and a memory race must be won (AC:H); attacker needs no privileges (PR:N) and full user-context compromise yields C/I/A High.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:19 cve.org
HIGH 7.5

DescriptionCVE.org

Use after free in Remote Desktop Client allows an unauthorized attacker to execute code over a network.

Executive ViewAI

Why It Matters

Windows Remote Desktop Client (mstsc) contains a high-severity use-after-free vulnerability that could let an attacker-controlled RDP server execute code as the connecting user across a wide range of supported Windows desktop and server builds. No public exploit identified at time of analysis, and a patch is available per vendor advisory; exploitation requires the victim to initiate an outbound RDP session to a hostile endpoint. Leadership should prioritize patching and user awareness because the client is ubiquitous and successful exploitation would grant an attacker the victim's user privileges.

Business Impact: Medium
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.6%
Top 54% exploitable
Prevalence
Ubiquitous
RDP client ships built into every supported Windows desktop and server edition
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.6%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Medium
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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