CVE-2026-109254 in FreeRDP
Summary
by MITRE • 10/12/2026
FreeRDP 2.1.0 before 3.32.0 contains a use-after-free vulnerability in the static rdpsnd channel disconnect path, which frees audio formats and device without joining play_thread. A malicious RDP server can disconnect while asynchronous Wave2 playback processes queued PDUs, causing the client to read freed heap memory and crash.
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Analysis
by VulDB Data Team • 10/12/2026
The identified vulnerability resides within the FreeRDP implementation of the Remote Desktop Protocol (RDP) audio subsystem, specifically affecting versions from 2.1.0 up to but not including 3.32.0. This flaw is categorized as a use-after-free condition located in the static rdpsnd channel disconnect path. The core technical deficiency involves improper synchronization during resource cleanup operations. When an RDP session terminates or experiences a disconnection event, the client application proceeds to free audio format structures and associated device handles. However, this deallocation process occurs without ensuring that the play_thread is properly joined or halted before memory release. This race condition allows for a scenario where asynchronous Wave2 playback processes continue to operate on queued Protocol Data Units (PDUs) even after their underlying memory resources have been reclaimed by the system allocator.
From an operational perspective, this vulnerability enables a malicious RDP server to trigger a denial of service against the client application with minimal effort. By initiating a disconnection sequence while asynchronous audio processing is actively handling pending PDUs, the attacker forces the client into an invalid state where it attempts to access memory that has already been freed. The immediate consequence of this out-of-bounds read operation is typically a segmentation fault or application crash, resulting in service disruption for the end user. While modern operating systems and heap allocators often provide some level of protection against exploitation through randomization and guard pages, making reliable code execution difficult, the reliability of the denial of service impact remains high across various platforms and configurations.
In terms of industry standard classifications, this vulnerability aligns with CWE-416, which describes Use After Free errors where a pointer is used after it has been freed, leading to undefined behavior. Furthermore, within the MITRE ATT&CK framework, this flaw facilitates techniques associated with Denial of Service (T1499) and potentially Memory Corruption (T1203), depending on whether an attacker can leverage the memory access for further exploitation beyond simple crashes. The lack of proper thread synchronization during resource teardown is a common pitfall in network-facing applications that handle asynchronous streams, highlighting the critical need for strict lifecycle management of background threads interacting with shared heap resources.
To mitigate this vulnerability, organizations must ensure that all instances of FreeRDP are updated to version 3.32.0 or later, where the disconnect path has been corrected to properly synchronize thread termination before memory deallocation. For environments unable to patch immediately due to compatibility constraints, deploying network-level access controls can restrict connections from untrusted RDP servers. Additionally, implementing strict input validation and monitoring for abnormal disconnection patterns may help detect potential exploitation attempts in real-time. It is also advisable to review application logs for frequent crashes or segmentation faults originating from the audio subsystem as an indicator of compromise activity targeting this specific flaw.