CVE-2026-67304 in FreeRDP
Summary
by MITRE • 08/01/2026
FreeRDP before 3.29.0 contains a null pointer dereference vulnerability in smartcard device control request cleanup when reader-state decoding fails. Attackers can send malformed smartcard IRP requests with non-zero cReaders and truncated reader-state data to crash the process via null pointer access in free_reader_states functions.
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Analysis
by VulDB Data Team • 08/01/2026
This vulnerability exists within FreeRDP versions prior to 3.29.0 and represents a critical null pointer dereference flaw in the smartcard device control request handling mechanism. The issue specifically manifests during the cleanup phase of smartcard operations when processing reader-state decoding, creating an exploitable condition that can lead to remote process crashes. The vulnerability stems from insufficient input validation and error handling within the smartcard subsystem, where malformed IRP (I/O Request Packet) requests containing non-zero cReaders values with truncated reader-state data can trigger the null pointer access.
The technical implementation of this flaw occurs in the free_reader_states function where the software attempts to clean up smartcard reader state information without proper validation of the incoming data structure. When attackers craft malicious IRP requests with malformed reader-state data, the decoding process fails and leaves pointers in an invalid state, resulting in a null pointer dereference during cleanup operations. This type of vulnerability falls under CWE-476 which specifically addresses NULL Pointer Dereference conditions, making it particularly dangerous as it can be exploited to cause denial of service or potentially enable further exploitation if combined with other vulnerabilities.
The operational impact of this vulnerability extends beyond simple process crashes, as it can be leveraged in remote code execution scenarios within environments where FreeRDP is used for remote desktop connections. Attackers can exploit this weakness by sending specially crafted smartcard requests through RDP connections, potentially causing service disruption, system instability, and denial of access to legitimate users. The vulnerability affects any system running FreeRDP versions before 3.29.0 that supports smartcard authentication or device redirection features, making it particularly concerning for enterprise environments that rely on remote desktop protocols for secure access.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059 which involves executing commands through remote services, and T1489 which encompasses denial of service attacks. The exploitation pathway typically involves establishing a remote RDP session and then sending malicious smartcard requests that trigger the null pointer dereference in the cleanup code path. Organizations using FreeRDP for remote desktop services should prioritize immediate patching to version 3.29.0 or later, as this update includes proper input validation and error handling for smartcard reader state data processing. Additionally, network segmentation and monitoring of RDP traffic can help detect and prevent exploitation attempts while implementing proper access controls and limiting smartcard device redirection capabilities where possible.
The root cause analysis reveals that the vulnerability stems from inadequate defensive programming practices in the smartcard subsystem, specifically the lack of bounds checking on incoming reader-state data and insufficient error recovery mechanisms. This flaw demonstrates the importance of robust input validation and proper resource management in security-critical applications, particularly those handling external device communications through remote protocols. Organizations should implement comprehensive testing procedures that include fuzzing of smartcard interfaces and other device control mechanisms to identify similar vulnerabilities before they can be exploited in production environments.