CVE-2022-23477 is a medium-severity vulnerability affecting the open-source project xrdp, which provides graphical login capabilities to remote machines via the Microsoft Remote Desktop Protocol (RDP). The vulnerability exists in versions of xrdp prior to 0.9.21 and is caused by a classic buffer overflow in the audin_send_open() function. Specifically, the flaw arises from a failure to properly check the size of input data before copying it into a buffer, violating secure coding practices as described in CWE-120. This unchecked buffer copy can lead to memory corruption, potentially allowing an attacker to execute arbitrary code or cause a denial of service (DoS) by crashing the xrdp service. The vulnerability does not currently have any known exploits in the wild, and no workarounds are available other than upgrading to version 0.9.21 or later where the issue has been fixed. Because xrdp is a widely used open-source RDP server alternative, particularly on Linux systems, this vulnerability poses a risk to any organization using vulnerable versions for remote desktop access. Exploitation would require an attacker to connect to the xrdp service and send specially crafted input to trigger the buffer overflow in audin_send_open(), which handles audio redirection during RDP sessions. The flaw affects confidentiality, integrity, and availability by potentially allowing remote code execution or service disruption without authentication, as RDP services are often exposed to internal or external networks. The lack of known exploits suggests limited current active threat, but the potential impact warrants prompt remediation.

For European organizations, the impact of CVE-2022-23477 can be significant, especially for those relying on xrdp to provide remote desktop access to Linux servers or workstations. Successful exploitation could allow attackers to gain unauthorized remote code execution capabilities, leading to full system compromise, data theft, or lateral movement within corporate networks. This is particularly critical for sectors with sensitive data such as finance, healthcare, and government agencies. Additionally, disruption of remote access services could impact business continuity and operational efficiency. Since xrdp is often deployed in environments where Microsoft RDP clients are used to access Linux hosts, organizations that have not updated to the patched version remain vulnerable. The vulnerability's medium severity indicates a moderate risk, but the ease of exploitation without authentication and the potential for remote code execution elevate the threat level. European organizations with remote access infrastructure exposed to untrusted networks or insufficiently segmented internal networks face increased risk. The absence of known exploits reduces immediate threat but should not lead to complacency given the potential for future weaponization.

Upgrade all xrdp installations to version 0.9.21 or later immediately to apply the official patch addressing the buffer overflow in audin_send_open(). Restrict network access to xrdp services using firewall rules or VPNs to limit exposure only to trusted users and networks, reducing the attack surface. Implement network segmentation to isolate systems running xrdp from critical infrastructure and sensitive data repositories. Monitor network traffic for unusual or malformed RDP session initiation attempts that could indicate exploitation attempts targeting the audin_send_open() function. Regularly audit and inventory remote access solutions to ensure no legacy or unsupported versions of xrdp remain in use. Consider disabling audio redirection features in xrdp configurations if not required, as the vulnerability is in the audio channel handling code. Employ endpoint detection and response (EDR) tools to detect anomalous process behavior or memory corruption indicative of exploitation attempts. Educate system administrators and security teams about this vulnerability and ensure timely patch management processes are in place.