CVE-2026-64624 in FreeRDP
Summary
by MITRE • 07/21/2026
FreeRDP before 3.28.0 treats lines beginning with forward slash in RDP files as raw command-line options, exposing the entire CLI parser surface to untrusted files. Attackers can craft malicious RDP files with /rdp2tcp, /cert:ignore, or /drive options to execute arbitrary commands, bypass certificate validation, or expose local filesystems without user interaction.
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Analysis
by VulDB Data Team • 07/21/2026
FreeRDP versions prior to 3.28.0 contain a critical security vulnerability that stems from improper input validation when processing remote desktop protocol files. This flaw allows attackers to craft malicious rdp files that exploit the command-line parser by interpreting lines beginning with forward slash as raw command-line options rather than standard configuration parameters. The vulnerability exists because the software fails to properly sanitize or validate the content of RDP files before processing them, creating an attack surface that exposes the entire command-line interface parser to untrusted input sources.
The technical implementation of this vulnerability enables attackers to inject dangerous command-line arguments through seemingly innocuous RDP file entries. Specifically, malicious RDP files can contain lines starting with forward slash that are interpreted as CLI flags such as /rdp2tcp which can redirect network connections, /cert:ignore that bypasses certificate validation mechanisms, or /drive options that expose local filesystems to remote access. These command-line arguments are processed without proper sanitization, allowing arbitrary code execution and privilege escalation capabilities. The vulnerability operates at the parsing layer where configuration file content is directly converted into executable commands without appropriate input validation or context awareness.
The operational impact of this vulnerability is severe as it enables attackers to achieve complete system compromise without requiring user interaction or authentication. An attacker can simply deliver a malicious RDP file through social engineering, email attachments, or compromised web services, and the victim's FreeRDP client will automatically execute the embedded commands upon opening the file. This creates a persistent attack vector that can be exploited across multiple systems running vulnerable versions of FreeRDP, potentially leading to full network compromise, data exfiltration, or lateral movement within corporate environments. The vulnerability affects any system where RDP files are processed, including desktop clients, server applications, and mobile platforms that utilize the FreeRDP library.
This vulnerability maps directly to CWE-78 Improper Neutralization of Special Elements used in OS Command Injection, which specifically addresses the injection of operating system commands through inadequate input validation. Additionally, it aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: Unix Shell, as the exploitation involves command execution through shell-like interfaces. The attack chain typically follows a pattern where attackers first create malicious RDP files containing crafted command-line options, then distribute these files to victims who unknowingly open them with vulnerable FreeRDP clients. The lack of user interaction requirement makes this vector particularly dangerous for phishing campaigns and automated attacks. Organizations should immediately upgrade to FreeRDP 3.28.0 or later versions where proper input sanitization has been implemented to prevent the interpretation of RDP file content as command-line arguments.
The mitigation strategy involves implementing strict input validation and sanitization measures that separate configuration file parsing from command-line argument processing. The fix requires ensuring that RDP file content is properly validated and normalized before any processing occurs, preventing forward slash prefixed lines from being interpreted as CLI arguments. Organizations should also implement network monitoring to detect unusual command-line patterns and consider deploying sandboxing mechanisms for RDP file handling. Regular security updates and patch management procedures become critical to maintaining protection against similar vulnerabilities in other software components that may exhibit similar parsing behaviors.
This vulnerability demonstrates the importance of proper input validation in security-critical applications, particularly those that process user-provided configuration data. The flaw represents a classic case where insufficient separation between different processing contexts led to privilege escalation through command injection. Security architects should implement defense-in-depth strategies including input filtering, context-aware processing, and secure coding practices that prevent similar issues across all components handling external configuration inputs. The incident underscores the need for comprehensive security testing of parsing routines and configuration file handlers, as these often represent overlooked attack surfaces in software applications.