CVE-2026-114046 in FreeRDP
Summary
by MITRE • 10/21/2026
FreeRDP 3.0.0 before 3.32.0 contains a null-pointer dereference in the smartcard emulation backend that accepts a null per-reader name in SCardGetStatusChange requests. A malicious RDP server can send a crafted reader-state entry with a null szReader, causing strcmp or _wcscmp to crash the client process.
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Analysis
by VulDB Data Team • 10/21/2026
The vulnerability identified within FreeRDP versions prior to 3.32.0 represents a critical security flaw located in the smartcard emulation backend subsystem. This component is responsible for managing virtual smart card readers and facilitating communication between the remote desktop session and local or networked cryptographic hardware. The specific defect arises from an insufficient validation of input parameters received during SCardGetStatusChange requests, which are standard API calls used to query the status of connected smart card readers. In a typical operation, this function expects valid string pointers for reader names to perform state comparisons against currently active devices. However, due to inadequate boundary checking and null-pointer verification within the codebase, the application fails to reject or properly handle cases where the szReader field is explicitly set to NULL by the sender of the request.
From a technical perspective, this flaw constitutes an improper input validation error that leads directly to memory corruption via dereferencing. When a malicious RDP server constructs and transmits a crafted reader-state entry containing a null pointer for the szReader attribute, FreeRDP proceeds to pass this invalid reference into standard C library string comparison functions such as strcmp or _wcscmp. These functions assume their input arguments are valid memory addresses pointing to null-terminated strings. Upon receiving a NULL argument, these libraries attempt to read from address zero, which is typically unmapped in modern operating system environments for security reasons. This action triggers an immediate segmentation fault or access violation exception within the client process context.
The operational impact of this vulnerability is significant, particularly regarding availability and service continuity. Since FreeRDP operates as a client application connecting to remote desktop servers, exploitation requires interaction with a compromised or malicious server infrastructure. An attacker controlling such a server can exploit this flaw by sending specifically crafted SCardGetStatusChange packets during the session initialization or maintenance phases. The successful execution of this attack results in the immediate termination of the FreeRDP process on the client machine. This denial-of-service condition disrupts the user's remote desktop session, potentially causing loss of unsaved work and requiring manual intervention to restart the application. In enterprise environments where persistent RDP sessions are common, such abrupt crashes can lead to productivity losses and increased helpdesk overhead for incident response and recovery.
This vulnerability aligns with Common Weakness Enumeration category CWE-476, which defines NULL Pointer Dereference as a weakness occurring when software dereferences a pointer that it expects to be valid but is actually null. Furthermore, the attack vector corresponds to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter or potentially T1203 if viewed through the lens of exploitation for disruption rather than code execution. While this specific instance primarily results in a crash rather than arbitrary code execution due to modern memory protection mechanisms like ASLR and DEP, it serves as a potential precursor for more complex attacks if combined with other vulnerabilities that allow heap or stack manipulation prior to the dereference point.
Mitigation strategies focus on both immediate patching and architectural hardening. The primary remediation is to upgrade FreeRDP to version 3.32.0 or later, where developers have implemented robust input validation checks to ensure that szReader pointers are not null before being passed to string comparison functions. Organizations should also enforce strict network segmentation policies to limit exposure of RDP clients to untrusted networks and implement application whitelisting to detect anomalous process terminations. Additionally, security teams should monitor for unusual patterns in remote desktop session logs that might indicate repeated connection attempts from suspicious sources attempting to trigger this denial-of-service condition. Regular vulnerability scanning and patch management cycles are essential to maintain the integrity of remote access infrastructure against such client-side exploitation vectors.