CVE-2026-41252 in xrdp
Summary
by MITRE • 07/20/2026
xrdp is an open source RDP server. Versions 0.10.6 and prior contain a missing bounds check in xrdp, which allows a heap-based buffer overflow when operating in vnc-any mode. The issue occurs during the handling of RFB protocol color map messages from a VNC server, where incoming color indices are not properly validated. A malicious VNC server can exploit this flaw by sending crafted messages with out-of-range values, leading to an out-of-bounds write on the heap. This memory corruption can result in a denial of service (DoS) or potentially allow remote code execution (RCE) prior to authentication. This issue has been fixed in version 0.10.6.1.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/21/2026
The xrdp vulnerability represents a critical heap-based buffer overflow flaw that affects versions 0.10.6 and earlier of this widely-used open source RDP server implementation. This security weakness exists within the vnc-any mode functionality where xrdp operates as a bridge between RDP clients and VNC servers, creating a complex attack surface that combines elements from both protocols. The vulnerability stems from inadequate input validation mechanisms during the processing of RFB (Remote Framebuffer) protocol color map messages, which are essential components in VNC server communications. When operating in vnc-any mode, xrdp must translate and forward VNC protocol elements to RDP clients, making it particularly susceptible to protocol-specific attacks that exploit implementation gaps in this translation layer.
The technical flaw manifests as a missing bounds check during the handling of color map messages from VNC servers, specifically when processing incoming color indices. This omission creates a heap-based buffer overflow condition where malicious VNC servers can craft specially formatted messages containing out-of-range color index values that exceed the allocated memory boundaries. The vulnerability occurs because xrdp fails to validate the range of color indices before writing them to heap-allocated buffers, allowing attackers to manipulate memory layout and potentially overwrite adjacent heap data structures. This type of memory corruption represents a classic buffer overflow scenario that can be exploited to achieve arbitrary code execution or denial of service conditions, particularly when the vulnerable system operates in vnc-any mode where such protocol translation is actively performed.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable remote code execution before authentication occurs, making it particularly dangerous in environments where xrdp serves as a gateway for remote desktop access. Attackers can exploit this flaw by establishing connections to vulnerable xrdp instances and presenting malicious VNC servers that send crafted color map messages with oversized indices. The vulnerability affects systems where xrdp is configured to operate in vnc-any mode, which is commonly used for interoperability between different remote desktop protocols. This attack vector represents a significant threat to organizations relying on xrdp as their primary RDP server implementation, as it can be exploited without requiring authentication credentials or network privileges beyond establishing the initial connection. The severity of this vulnerability is amplified by the fact that it occurs during protocol translation rather than during the actual authentication process, making traditional security controls less effective against such attacks.
Security professionals should note that this vulnerability aligns with CWE-121 heap-based buffer overflow conditions and represents a clear example of insufficient input validation in protocol handling components. The attack surface is particularly relevant to organizations using xrdp in enterprise environments where it serves as a critical component for remote desktop access and system administration. Mitigation strategies should include immediate deployment of version 0.10.6.1 or later, which contains the necessary bounds checking fixes. Organizations should also implement network segmentation controls to limit exposure of vulnerable xrdp instances and consider disabling vnc-any mode if it is not required for operations. The vulnerability demonstrates the importance of thorough input validation in protocol translation layers and aligns with ATT&CK techniques related to privilege escalation through memory corruption exploits, particularly when considering that successful exploitation could lead to system compromise before authentication occurs.