CVE-2025-26597 is a high-severity buffer overflow vulnerability affecting X.Org and Xwayland, components widely used in Unix-like operating systems to provide graphical display server functionality. The flaw arises in the function XkbChangeTypesOfKey(), which manages keyboard key symbol tables and their associated actions. Specifically, when this function is called with a group parameter set to 0, it resizes the key symbols table to zero but does not adjust the key actions accordingly. If the function is subsequently called with a non-zero group value, the mismatch in sizes between the key symbols table and the key actions array leads to a buffer overflow condition. This improper restriction of operations within the bounds of a memory buffer can result in memory corruption. Given the nature of buffer overflows, this vulnerability can be exploited to execute arbitrary code with the privileges of the affected process, potentially leading to full system compromise. The CVSS v3.1 score of 7.8 reflects a high impact on confidentiality, integrity, and availability, with low attack complexity but requiring local privileges and no user interaction. The vulnerability affects versions from 0 up to 22.0.0 of the affected software. Although no known exploits are currently reported in the wild, the technical details indicate a significant risk if exploited, especially on systems relying on X.Org or Xwayland for graphical interfaces.

For European organizations, this vulnerability poses a significant threat particularly to enterprises and institutions using Linux or Unix-like systems with X.Org or Xwayland for graphical environments. The ability to execute arbitrary code locally can lead to privilege escalation, data breaches, and disruption of critical services. Sectors such as finance, government, healthcare, and critical infrastructure, which often rely on Linux-based systems for servers and workstations, could face operational disruptions and data confidentiality breaches. Additionally, since the vulnerability requires local privileges, it could be leveraged by attackers who have already gained limited access, enabling lateral movement and deeper infiltration within networks. The high impact on confidentiality, integrity, and availability underscores the risk of data theft, system manipulation, and denial of service. The absence of known exploits currently provides a window for proactive mitigation before widespread exploitation occurs.

European organizations should prioritize patching affected systems by upgrading X.Org and Xwayland to versions beyond 22.0.0 once patches are available. Until patches are released, organizations should implement strict access controls to limit local user privileges, minimizing the risk of exploitation by untrusted users. Employing application whitelisting and monitoring for anomalous behavior related to X.Org processes can help detect exploitation attempts. Network segmentation should be enforced to restrict lateral movement from compromised hosts. Additionally, organizations should audit and harden systems to reduce the attack surface, including disabling unnecessary graphical services on servers and enforcing the principle of least privilege for all users. Regular vulnerability scanning and penetration testing focused on local privilege escalation vectors will help identify potential exploitation paths. Finally, maintaining up-to-date intrusion detection systems with signatures for potential buffer overflow exploits targeting X.Org can aid in early detection.