The Jenkins User1st uTester Plugin versions 1.1 and earlier contain a vulnerability identified as CVE-2025-53678, where the plugin stores the uTester JWT token unencrypted in the global configuration file on the Jenkins controller. This configuration file is accessible to users who have access to the Jenkins controller's file system, which may include system administrators or other users with elevated privileges on the Jenkins server. The unencrypted storage of sensitive JWT tokens violates secure credential storage best practices (CWE-311: Missing Encryption of Sensitive Data). An attacker or unauthorized user with file system access can read the token and potentially use it to impersonate the Jenkins plugin or access services that trust the JWT token, leading to confidentiality breaches. The vulnerability has a CVSS 3.1 base score of 6.5, reflecting medium severity, with an attack vector of network (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), and no impact on integrity or availability (I:N/A:N). No patches or fixes are currently linked, and no exploits have been reported in the wild. The vulnerability primarily affects Jenkins controllers running the User1st uTester Plugin version 1.1 or earlier, which are used in continuous integration and testing environments. The risk is elevated in environments where multiple users have file system access to the Jenkins controller, increasing the chance of token exposure and misuse.

For European organizations, this vulnerability poses a significant confidentiality risk, especially for those relying on Jenkins for CI/CD pipelines and using the User1st uTester Plugin. Exposure of the JWT token can lead to unauthorized access to testing or monitoring services integrated with Jenkins, potentially allowing attackers to gather sensitive project information or manipulate test results indirectly. Although the vulnerability does not directly affect system integrity or availability, the stolen token could be leveraged in chained attacks to escalate privileges or move laterally within the network. Organizations with shared Jenkins environments or less restrictive file system permissions are particularly vulnerable. The impact is heightened in sectors with strict data protection regulations such as GDPR, where unauthorized disclosure of credentials could lead to compliance violations and reputational damage. Additionally, the lack of encryption in token storage reflects poor security hygiene, which could be indicative of other latent vulnerabilities in the environment.

European organizations should immediately audit access controls on Jenkins controller file systems to ensure only trusted administrators have access. Restrict file system permissions to prevent unauthorized users from reading Jenkins configuration files. Until an official patch is released, consider removing or disabling the User1st uTester Plugin if it is not essential. If the plugin is required, isolate Jenkins controllers in secure network segments with strict access controls and monitor access logs for suspicious activity. Rotate or invalidate any JWT tokens stored by the plugin to prevent misuse. Implement additional encryption layers or secrets management solutions to protect sensitive tokens and credentials used by Jenkins plugins. Regularly update Jenkins and its plugins to the latest versions once patches become available. Educate DevOps and system administrators about secure credential storage practices and the risks of exposing tokens in plaintext. Finally, integrate file integrity monitoring to detect unauthorized changes or access to Jenkins configuration files.