Jenkins Gatling Plugin Vulnerability Enables Content-Security-Policy Bypass

A critical security vulnerability has been discovered in the Jenkins Gatling Plugin that allows attackers to bypass Content-Security-Policy protections, potentially exposing Jenkins instances to cross-site scripting attacks.

The vulnerability, assigned CVE-2025-5806 and classified as high severity, affects the latest version of the widely-used performance testing plugin and currently has no available fix, prompting security experts to recommend immediate downgrade actions.

The Jenkins Security Team released an advisory on June 6, 2025, detailing a significant cross-site scripting (XSS) vulnerability in the Gatling Plugin version 136.vb_9009b_3d33a_e.

The vulnerability, tracked as SECURITY-3588, represents a serious security concern for organizations using Jenkins for continuous integration and deployment workflows.

The vulnerability specifically targets the plugin’s report serving mechanism, which has been found to circumvent critical security protections that were implemented in Jenkins core versions 1.641 and 1.625.3.

The Gatling Plugin is extensively used in DevOps environments for performance testing and load simulation, making this vulnerability particularly concerning for enterprise deployments.

The plugin allows teams to integrate Gatling performance tests into their Jenkins pipelines and generates detailed reports for analysis.

However, the current implementation of the report serving functionality contains a fundamental flaw that undermines the security architecture of modern Jenkins installations.

The severity rating of “High” reflects the potential impact of successful exploitation, which could allow malicious actors to execute arbitrary JavaScript code within the context of a user’s Jenkins session.

This type of attack could lead to session hijacking, unauthorized access to sensitive build information, or manipulation of CI/CD processes.

Jenkins Gatling Plugin Vulnerability

The core issue lies in how the Gatling Plugin serves reports to users within the Jenkins interface.

Content-Security-Policy (CSP) is a crucial web security standard that helps prevent XSS attacks by restricting the sources from which browsers can load and execute scripts, stylesheets, and other resources.

Jenkins implemented these protections several years ago to enhance the security posture of its web interface and protect against malicious content injection.

However, the Gatling Plugin’s report serving mechanism bypasses these CSP protections entirely, creating a security gap that attackers can exploit.

When users with the ability to modify report content craft malicious payloads, they can inject scripts that will execute in other users’ browsers when they view the reports.

This bypass mechanism effectively neutralizes one of Jenkins’ key defense mechanisms against XSS attacks.

The vulnerability requires that attackers have some level of access to modify report content, which typically means they need legitimate access to the Jenkins instance or the ability to influence the build process that generates Gatling reports.

While this limits the attack vector somewhat, it still represents a significant risk in environments where multiple users or teams share Jenkins infrastructure.

Content-Security-Policy

Perhaps most concerning is the current lack of an available fix for this vulnerability.

According to Report, Jenkins Security Team has explicitly stated that no patches are available for the affected Gatling Plugin version, leaving users in a difficult position.

This situation highlights the challenges faced by open-source projects in maintaining security across numerous community-contributed plugins.

As an interim security measure, the advisory recommends that affected users downgrade to Gatling Plugin version 1.3.0, which predates the vulnerable code implementation.

While downgrading may result in the loss of newer features and functionality, it provides immediate protection against potential exploitation of this XSS vulnerability.

Organizations using the affected plugin should assess their risk exposure and implement the recommended downgrade as soon as possible.

Additionally, they should monitor the Jenkins security advisories and plugin update channels for information about when a permanent fix becomes available.

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