CVE-2026-50445: Windows RDP Information Disclosure Flaw

CVE-2026-50445 Overview

CVE-2026-50445 is a buffer over-read vulnerability in the Windows Remote Desktop Protocol (RDP) implementation. An unauthorized attacker can exploit the flaw over a network to disclose sensitive information from the target system's memory. Exploitation requires user interaction, which limits opportunistic mass exploitation but still enables targeted attacks against exposed RDP endpoints.

The vulnerability is classified under [CWE-126] (Buffer Over-read) and affects Microsoft Windows RDP components. Successful exploitation can leak memory contents that may include credentials, cryptographic material, or other process data useful for follow-on intrusion.

Critical Impact
Network-based information disclosure from Windows RDP memory without authentication, enabling reconnaissance and credential harvesting for further compromise.

Affected Products

Microsoft Windows (Remote Desktop Protocol component)
Refer to the Microsoft Security Update Guide for the authoritative list of affected builds
Systems with RDP enabled and exposed to untrusted networks

Discovery Timeline

2026-07-14 - CVE-2026-50445 published to NVD
2026-07-15 - Last updated in NVD database

Technical Details for CVE-2026-50445

Vulnerability Analysis

The vulnerability resides in how Windows RDP parses inbound protocol data. A buffer over-read occurs when the code reads past the intended end of a memory buffer, returning adjacent process memory to the attacker's session. Because RDP handles the read as valid data, the leaked bytes can be reflected back through protocol responses or session state.

The flaw does not modify memory or execute code directly. Instead, it exposes information that an attacker can use to map memory layout, extract secrets, or defeat mitigations such as Address Space Layout Randomization (ASLR). Information disclosure of this class often serves as a precursor to remote code execution chains targeting the same service.

Root Cause

The root cause is missing or incorrect boundary validation on a length field within an RDP protocol structure. When the parser trusts an attacker-controlled length without confirming it against the actual buffer size, subsequent read operations extend into unrelated memory regions. This behavior matches the [CWE-126] pattern of reading data beyond the end of an intended buffer.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker typically induces a victim to connect to a malicious RDP server, at which point crafted server responses trigger the over-read on the client. The exploitation flow can be summarized as follows:

The attacker stands up a malicious RDP endpoint or coerces a session to one.
The victim initiates or accepts an RDP connection, satisfying the user interaction requirement.
The malicious server sends a crafted protocol message with manipulated length fields.
The RDP client reads beyond the allocated buffer and returns memory contents to the attacker.

No authentication is required, and no privileges are needed on the target system prior to exploitation.

Detection Methods for CVE-2026-50445

Indicators of Compromise

Outbound RDP (TCP/3389) connections from workstations to unknown or low-reputation external hosts
RDP client processes (mstsc.exe) initiating connections following phishing emails or malicious links
Anomalous RDP session terminations or protocol errors clustered around specific external destinations

Detection Strategies

Inspect network telemetry for RDP sessions crossing the perimeter to non-corporate infrastructure
Correlate mstsc.exe launches with parent processes such as browsers or email clients, which often indicate coerced connections
Alert on RDP handshake anomalies or malformed Protocol Data Units (PDUs) observed by network sensors

Monitoring Recommendations

Log all outbound RDP traffic and baseline expected destinations for jump hosts and administrative infrastructure
Monitor endpoint process telemetry for unusual mstsc.exe command lines referencing external IPs or .rdp files from untrusted paths
Track Windows event logs for RDP client connection events and correlate with user reports of unexpected prompts

How to Mitigate CVE-2026-50445

Immediate Actions Required

Apply the security update referenced in the Microsoft Security Update Guide to all affected Windows systems
Block outbound TCP/3389 at the network perimeter except to explicitly approved administrative destinations
Educate users to reject unexpected RDP connection prompts and .rdp file attachments

Patch Information

Microsoft has published guidance and update packages for CVE-2026-50445 through the Microsoft Security Update Guide. Administrators should identify affected builds in their environment and deploy the corresponding cumulative update through Windows Update, Windows Server Update Services (WSUS), or their preferred patch management tooling.

Workarounds

Restrict outbound RDP with host-based and perimeter firewall rules until patches are deployed
Require RDP connections to route through a Remote Desktop Gateway that enforces destination allowlists
Disable the RDP client on systems that do not require outbound remote desktop functionality

bash

# Block outbound RDP on Windows endpoints via firewall rule
New-NetFirewallRule -DisplayName "Block Outbound RDP" `
  -Direction Outbound `
  -Protocol TCP `
  -RemotePort 3389 `
  -Action Block