CVE-2026-109944 in FreeRDP
Summary
by MITRE • 10/13/2026
FreeRDP 3.0.0 before 3.32.0 does not remove card handles when Emulate_SCardReleaseContext releases a smartcard-emulation context, so Emulate_SCardTransmit later looks up the deleted parent context and reaches a terminating WINPR_ASSERT. A malicious RDP server can crash a connecting client with smartcard emulation and redirection enabled by releasing a context, establishing another, and issuing SCardTransmit with the stale card handle.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified in FreeRDP versions prior to 3.32.0 represents a critical resource management flaw within the smartcard emulation subsystem, specifically affecting clients that have enabled both smartcard emulation and redirection features. This issue stems from an improper handling of lifecycle events for cryptographic token interfaces, where the application fails to correctly invalidate or remove internal references when a specific context is released by the operating system's security service provider interface. The core technical flaw lies in the Emulate_SCardReleaseContext function, which terminates the connection to the smart card reader but neglects to clear associated handles stored within the client’s local state structures. Consequently, subsequent operations that rely on these stale identifiers encounter undefined behavior rather than graceful error handling or proper re-initialization of resources.
When a malicious Remote Desktop Protocol server exploits this weakness, it can trigger a denial-of-service condition against the connecting client by orchestrating a specific sequence of API calls designed to abuse the state inconsistency. The attack vector involves the server instructing the client to release an existing smartcard context via Emulate_SCardReleaseContext. Immediately following this release, the attacker causes the establishment of a new context and then issues an SCardTransmit command referencing the card handle from the previously released but not fully cleaned-up context. Because the internal lookup mechanism attempts to resolve operations against a parent context that has already been deallocated or marked for termination, the underlying WINPR assertion library detects this invalid state reference. This detection triggers a terminating assertion failure, which results in an immediate and unhandled crash of the FreeRDP client application process.
From a security architecture perspective, this vulnerability is classified under CWE-416, Use After Free, as the system attempts to utilize memory or object references that have been invalidated by prior deallocation logic. The operational impact is severe for environments relying on remote desktop sessions with hardware token integration, such as corporate networks utilizing smart cards for multi-factor authentication and secure access control. An attacker capable of controlling or spoofing an RDP server can remotely crash the client software without requiring any user interaction beyond establishing a connection that supports smartcard redirection. This denial-of-service capability disrupts productivity and may interfere with security workflows if users are forced to re-authenticate using physical tokens after every session reset caused by such crashes.
The exploitation of this flaw aligns with ATT&CK technique T1499, Endpoint Denial of Service, as it involves manipulating system resources to degrade the availability of a specific endpoint component. Furthermore, it reflects weaknesses in input validation and state management that are common in complex interoperability layers between operating systems and remote protocol implementations. The failure to properly synchronize handle lifecycles with context release operations indicates a gap in defensive coding practices regarding resource tracking within the emulation layer.
To mitigate this vulnerability, organizations must ensure that all FreeRDP clients are updated to version 3.32.0 or later, where the developers have implemented proper cleanup routines for smartcard handles upon context release. Until patching is complete, administrators should consider restricting access to RDP servers from untrusted networks and disabling smartcard redirection features if they are not strictly required for business operations. Additionally, deploying network-level authentication controls can help prevent unauthorized or malicious servers from initiating the specific sequence of commands needed to trigger this state inconsistency. Regular vulnerability scanning and patch management processes should be enforced to maintain resilience against such resource exhaustion attacks in remote access infrastructures.