CVE-2026-109938 in FreeRDP
Summary
by MITRE • 10/13/2026
Positive mapped-video coordinates overflow and abort FreeRDP clients A malicious or compromised RDP server can terminate a FreeRDP client after the user connects with video redirection enabled.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified involves a critical integer overflow within the coordinate mapping logic of the FreeRDP client, specifically affecting sessions where remote desktop protocol video redirection is active. This flaw allows an attacker who controls or has compromised the RDP server to manipulate specific data fields during the session initialization and rendering phases. By sending crafted packets containing maliciously calculated mapped-video coordinates, the server can trigger a buffer overflow condition within the client application. The core technical failure lies in the insufficient validation of coordinate boundaries before they are processed by the underlying graphics subsystems. When these out-of-bounds values are passed to memory allocation routines or array indexing operations, they result in an invalid memory access that causes the FreeRDP process to abort unexpectedly. This behavior effectively constitutes a denial of service against the client application rather than allowing for arbitrary code execution, as the immediate consequence is the termination of the program instance.
From a technical perspective, this issue aligns with CWE-190, which describes integer overflow or wraparound errors that can lead to buffer overflows and other memory corruption issues. The attack vector requires an active connection where video redirection has been explicitly enabled by the user or administrator, indicating that the vulnerability is not triggered in standard text-only remote desktop sessions. The exploitation relies on the server sending specific RDP PDU (Protocol Data Unit) messages containing malformed coordinate data during the graphics pipeline processing stage. Because FreeRDP operates as a client-side application, the impact is localized to the machine running the software, preventing lateral movement or direct compromise of network infrastructure but severely disrupting user productivity and availability of remote resources.
The operational impact of this vulnerability is primarily centered on service disruption for organizations relying on FreeRDP for virtual desktop infrastructure or remote support scenarios involving high-bandwidth video streaming. An attacker can remotely terminate active sessions without requiring authentication beyond the initial connection handshake, provided they control the server endpoint. This capability undermines the reliability and availability guarantees expected from enterprise remote access solutions. In environments where automated scripts or persistent connections rely on uninterrupted FreeRDP processes, such abrupt terminations can lead to data loss in unsaved workloads or trigger failover mechanisms that may themselves introduce additional security risks if not properly secured.
Mitigation strategies should focus on both immediate patching and architectural hardening. Users must upgrade to the latest version of FreeRDP where this coordinate validation logic has been corrected to ensure bounds checking is performed before memory operations are executed. Network administrators should consider implementing strict access control lists for RDP servers, ensuring that only trusted endpoints can initiate video redirection sessions. Additionally, deploying intrusion detection systems capable of identifying anomalous patterns in RDP traffic may help detect exploitation attempts in real-time. Organizations relying on this software should also evaluate alternative remote desktop solutions with more rigorous security auditing histories if the risk profile associated with maintaining FreeRDP becomes unacceptable due to ongoing maintenance burdens or historical vulnerability trends.