CVE-2026-67296 in FreeRDP
Summary
by MITRE • 08/01/2026
FreeRDP before 3.29.0 contains a denial of service vulnerability in the RDPEI server channel handler that fails to validate maximum PDU body length before stream allocation. A malicious RDP client can send a header-only RDPEI message with a large declared body length to force excessive memory allocation on the server.
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Analysis
by VulDB Data Team • 08/01/2026
This vulnerability affects FreeRDP versions prior to 3.29.0 and represents a classic denial of service flaw in the RDPEI server channel handler component. The issue stems from inadequate input validation where the system fails to properly verify the maximum PDU body length before proceeding with stream allocation operations. This represents a failure in defensive programming practices and constitutes a direct violation of secure coding principles that should prevent buffer overflows and memory exhaustion conditions.
The technical flaw manifests when a malicious RDP client sends a header-only RDPEI message containing a deliberately inflated declared body length field. This allows the attacker to manipulate the server into allocating excessive memory resources based on the false length specification rather than the actual payload size. The vulnerability operates at the protocol level within the Remote Desktop Protocol implementation, specifically targeting the Input Virtual Channel handling mechanism that processes mouse and keyboard events in RDP sessions.
From an operational impact perspective, this vulnerability enables a remote attacker to consume excessive server resources through memory allocation exhaustion, potentially leading to system instability, service disruption, or complete denial of service for legitimate users. The attack requires minimal privileges and can be executed remotely without authentication, making it particularly dangerous in environments where RDP servers are exposed to untrusted networks. This aligns with ATT&CK technique T1499.004 for network denial of service attacks and represents a form of resource exhaustion attack.
The vulnerability demonstrates poor adherence to industry standards including CWE-129 Input Validation and CWE-772 Insufficient Resource Management, where proper bounds checking should prevent allocation of memory beyond reasonable limits. Organizations running FreeRDP servers are particularly at risk as this affects core RDP functionality and can be exploited by attackers with minimal technical expertise. The impact extends beyond simple service disruption to potentially compromise availability for critical business applications that rely on remote desktop connectivity.
Mitigation strategies should include immediate deployment of FreeRDP version 3.29.0 or later which contains the necessary patch to validate PDU body lengths before memory allocation occurs. Network segmentation and access controls should be implemented to limit exposure of RDP servers to trusted networks only, while monitoring systems should be configured to detect anomalous RDPEI message patterns. Additionally, implementing rate limiting and connection throttling mechanisms can help reduce the impact of such attacks by limiting the number of malicious connections that can be established within a given timeframe.