CVE-2025-4211 is a high-severity vulnerability classified under CWE-59 (Improper Link Resolution Before File Access, also known as 'Link Following') affecting the Qt framework, specifically its QFileSystemEngine component on Windows platforms. The root cause lies in the improper handling of temporary file paths generated via the Windows GetTempPath API. Qt's public APIs such as QDir::tempPath(), QStandardPaths with TempLocation, QTemporaryDir, and QTemporaryFile rely on this mechanism to create and manage temporary files and directories. Due to insufficient validation and resolution of symbolic links (symlinks) in these temporary paths, an attacker with limited privileges can manipulate the temporary file location to point to arbitrary files or directories. This manipulation can lead to symlink attacks where malicious files are introduced or legitimate files are overwritten, potentially resulting in unauthorized file access or privilege escalation. The vulnerability affects all Qt versions up to and including 5.15.18, all 6.x versions from 6.0.0 through 6.5.8, and from 6.6.0 through 6.8.1. It has been addressed in Qt versions 5.15.19, 6.5.9, 6.8.2, and 6.9.0. The CVSS 4.0 score of 7.3 reflects a high severity, with a complex vector indicating local attack vector, low attack complexity, partial privileges required, partial user interaction, and high impact on confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the vulnerability's nature and the widespread use of Qt in cross-platform applications make it a significant risk, especially for Windows-based deployments. The issue originates from a previous CVE (2024-38081), indicating a recurring problem in temporary file handling within Qt's core libraries.

For European organizations, the impact of CVE-2025-4211 can be substantial, particularly for those relying on Qt-based applications or developing software with Qt on Windows environments. Exploitation could allow attackers to perform symlink attacks leading to unauthorized access to sensitive files, data corruption, or privilege escalation, potentially compromising critical business applications. This can result in data breaches, disruption of services, and loss of integrity in software operations. Industries such as finance, healthcare, manufacturing, and critical infrastructure, which often use custom or commercial Qt applications, could face operational disruptions or regulatory compliance issues under GDPR if personal data is exposed. The vulnerability's exploitation requires local access and some user interaction, which may limit remote exploitation but does not eliminate risk in environments where users can be socially engineered or where insider threats exist. Additionally, the high impact on confidentiality, integrity, and availability means that successful exploitation could lead to severe consequences including ransomware deployment or persistent footholds within enterprise networks.

European organizations should prioritize updating Qt to the fixed versions: 5.15.19, 6.5.9, 6.8.2, or 6.9.0 as soon as possible. For organizations unable to immediately upgrade, temporary mitigations include restricting user permissions to prevent unauthorized creation or manipulation of symbolic links in temporary directories and monitoring file system activities related to temporary paths for suspicious behavior. Application developers should audit their use of Qt APIs related to temporary file handling and avoid relying on QDir::tempPath() or related functions without additional validation of the resolved paths. Employing application whitelisting and endpoint detection and response (EDR) solutions can help detect exploitation attempts. Additionally, enforcing strict access controls on temporary directories and implementing user education programs to reduce the risk of social engineering can further reduce exposure. Finally, organizations should integrate this vulnerability into their patch management and vulnerability scanning processes to ensure timely detection and remediation.