Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
ReconAttacker hosts malicious RDP server
-
DeliveryPhish victim with crafted .rdp file
-
ExploitVictim's client connects outbound
-
InstallServer returns malformed protocol response
-
C2Heap buffer overflow in client
-
ExecuteHijack execution flow
-
ImpactRun code as logged-in user
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution 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 initiate an RDP connection to an attacker-controlled server (UI:R in the CVSS vector), meaning the attacker must socially engineer the user into opening a malicious .rdp file, clicking an rdp:// URI, or otherwise launching the Remote Desktop Client against a hostile endpoint - this is a reverse/client-side attack, not a server-listening RDP exposure like BlueKeep. No prior authentication to any Microsoft system is needed (PR:N), but the high attack complexity (AC:H) indicates the attacker must win a non-trivial race or satisfy specific heap-state conditions for the overflow to yield reliable code execution. Exploitation is limited by the need for user interaction, by egress filtering that blocks outbound 3389 to untrusted networks, and by modern Windows mitigations (ASLR, CFG, heap hardening) that raise the bar on turning the overflow into RCE. |
| Impact | The CVSS vector AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H describes a network-reachable, unauthenticated flaw with full CIA impact but tempered by high attack complexity and required user interaction, which is why the base score lands at 7.5 rather than critical. There is no EPSS score, KEV listing, or public POC referenced in the provided data, so real-world exploitation pressure currently appears low and likely targeted rather than mass-scanned, since the victim must initiate an outbound RDP connection to attacker infrastructure. A notable conflict to flag: the description phrases the attacker as 'unauthorized' and over a 'network', yet the CVSS demands UI:R - defenders should interpret this as a reverse-RDP / malicious-server scenario rather than a wormable server-side bug like BlueKeep, and verify scope with Microsoft's advisory before deprioritizing. |
| Exploit ScenarioDerived | An attacker stands up a malicious RDP server and lures a target into connecting - typically via a phishing email containing a crafted .rdp file, a malicious link, or a poisoned shortcut on a compromised file share. When the victim's Remote Desktop Client negotiates the session, the rogue server returns a malformed protocol response that overflows a heap buffer in the client, allowing the attacker to execute arbitrary code in the user's context on the victim workstation. No public exploit identified at time of analysis, but the pattern is well-understood from prior RDP client CVEs. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Jun 09, 2026
Remote code execution in Microsoft Remote Desktop Client is possible when a user is lured into connecting to an attacker-controlled RDP server, where a heap-based buffer overflow (CWE-122) can be triggered to run arbitrary code on the client machine. The flaw was reported by Microsoft (secure@microsoft.com) and carries a CVSS 3.1 score of 7.5, reflecting high attack complexity and the requirement for user interaction. No public exploit identified at time of analysis, and the issue is not currently listed in CISA KEV.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update referenced at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42993 as the primary fix; exact patched build numbers should be pulled directly from the MSRC update guide for each affected Windows release. As compensating controls until patching completes, restrict outbound TCP/3389 (and UDP/3389) egress at the perimeter firewall so users cannot connect to arbitrary external RDP servers, enforce an allowlist of trusted internal RDP destinations via Group Policy, and disable or block .rdp file attachments at the email gateway to cut off the most common social-engineering delivery path; note that egress blocking will break legitimate remote-work scenarios that rely on connecting to cloud-hosted RDP/AVD endpoints, so scope exceptions accordingly. Additional vulnerability metadata is mirrored at https://vuldb.com/vuln/369637.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 17 packages in microsoft, euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The Remote Desktop Client is the Microsoft RDP client component used to initiate sessions over the Remote Desktop Protocol, which negotiates virtual channels and exchanges binary structures with a server. CWE-122 (Heap-based Buffer Overflow) indicates that data from the server is written into a heap-allocated buffer without sufficient size validation, corrupting adjacent heap metadata or object pointers. Because the vulnerable code runs in the client process, a malicious RDP server can shape responses (likely within a protocol message, virtual channel, or graphics/clipboard subsystem) to overflow the buffer and divert execution, mirroring the long history of RDP client-side parsing flaws.
Know when Windows 10 21h2 gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
1DescriptionCVE.org
Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
Executive ViewAI
Microsoft Remote Desktop Client is affected by a critical vulnerability (CVE-2026-42993) enabling remote code execution through user-initiated connections to malicious servers, directly threatening organizations supporting remote desktop access. This attack vector bypasses traditional perimeter defenses by targeting the client application rather than infrastructure. While no public exploit identified at time of analysis, immediate detection and mitigation measures are essential to prevent endpoint compromise.
Restrict RDP client connections to authorized servers via firewall policies and whitelisting; deploy advanced endpoint protection with behavioral monitoring for RDP client processes; conduct user awareness training on social engineering and untrusted server risks; enable network anomaly detection for unusual outbound RDP traffic patterns.
Threat Intelligence Overview
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.
Related Vulnerabilities in Remote Desktop Client Code Execution Flaws
View all 6More in Windows 10 21h2
View all<p>A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged fi
Windows MSDT (Microsoft Support Diagnostic Tool) allows remote code execution when called via the ms-msdt URL protocol f
Windows Search Remote Code Execution Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely explo
Internet Shortcut Files Security Feature Bypass Vulnerability. Rated high severity (CVSS 8.1), this vulnerability is rem
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour
Windows Kernel contains a TOCTOU race condition vulnerability allowing local privilege escalation, exploited by the OilR
Windows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables
Windows SMB contains an improper access control vulnerability (CVE-2025-33073, CVSS 8.8) enabling authenticated attacker
Windows Kernel Elevation of Privilege Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is low attack co
Why is Microsoft republishing a CVE from 2013? We are republishing CVE-2013-3900 in the Security Update Guide to update
Active Directory Domain Services contains an elevation of privilege vulnerability that allows authenticated domain users
Windows Kernel-Mode Driver Elevation of Privilege Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is l
EUVD-2026-35760
GHSA-79cp-qrf9-6hv3
NVD
CVE.org
EPSS
Vulnrichment
VulDB
Exploit-DB