Jenkins Gatling Plugin Flaw Allows CSP Bypass, Exposing Systems to Attack

On June 6, 2025, the Jenkins Project issued a security advisory (SECURITY-3588 / CVE-2025-5806) affecting the Gatling Plugin, a widely used tool for displaying performance test reports within the Jenkins automation server.

The vulnerability carries a high severity rating, with CVSS base scores ranging from 8.0 to 9.0 across different versions, indicating a significant risk to affected systems.

Vulnerability Overview and Technical Details

The core issue lies in Gatling Plugin version 136.vb_9009b_3d33a_e, which serves Gatling reports in a way that bypasses the Content-Security-Policy (CSP) protections introduced in Jenkins versions 1.641 and 1.625.3.

This bypass enables a cross-site scripting (XSS) vulnerability, classified as CWE-79—Improper Neutralization of Input During Web Page Generation.

Attackers with the ability to modify report content—even those with low-privileged access—can inject malicious scripts that execute in the context of other users’ browsers.

Such scripts could lead to theft of sensitive session cookies, unauthorized actions, and compromise of user credentials or sensitive information.

Technical Terms and Codes Involved:

• Content-Security-Policy (CSP): A security standard designed to prevent XSS by restricting the sources from which scripts and other resources can be loaded.
• Cross-Site Scripting (XSS): A vulnerability where malicious scripts are injected into web pages viewed by other users.
• CVE-2025-5806: The official identifier for this vulnerability.
• SECURITY-3588: The Jenkins internal advisory identifier.
• CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H: The Common Vulnerability Scoring System (CVSS) vector, indicating high confidentiality, integrity, and availability impacts.

Affected Versions and Mitigation Strategies

The vulnerability specifically affects Gatling Plugin versions up to and including 136.vb_9009b_3d33a_e.

Contrary to some documentation, earlier versions are not affected—this is due to a technical limitation in how advisory pages are rendered on jenkins.io.

Affected Plugin and Version Table

Plugin Name	Affected Version(s)	Not Affected (Clarification)
Gatling Plugin	Up to 136.vb_9009b_3d33a_e	Versions before the affected

As of the advisory’s publication, no official patch is available.

The Jenkins Project recommends downgrading to Gatling Plugin version 1.3.0 as a temporary mitigation measure.

Mitigation Strategies:

• Downgrade to Version 1.3.0: Until a fix is released, this is the primary recommendation.
• Restrict Report Modification: Limit who can modify Gatling report content to reduce the attack surface.
• Implement Additional Input Validation: Apply strict input validation and output encoding to prevent script injection.
• Review and Strengthen CSP Settings: Ensure that Content-Security-Policy headers are properly configured and enforced.
• Conduct Security Reviews: Perform thorough reviews of plugin configurations and user permissions.

Risk Assessment and Industry Response

The vulnerability has been assigned a high severity rating by multiple sources, including the Jenkins Project, CloudBees, and security researchers.

The CVSS base score of 8.0–9.0 reflects the potential for significant impact if exploited, though there is currently no evidence of active exploitation or a public proof-of-concept.

Security advisories and vulnerability databases, including NVD, GitHub Advisory Database, and Tenable, have all published detailed analyses.

The Exploit Prediction Scoring System (EPSS) estimates a low probability (0.04%) of exploitation activity in the next 30 days, but organizations are urged to remain vigilant.

Key Takeaways for Security Teams:

• Monitor for Updates: Stay informed about new releases or patches for the Gatling Plugin.
• Apply Least Privilege: Restrict user permissions to only what is necessary.
• Enhance Monitoring: Implement monitoring for unusual activity related to report generation and access.
• Educate Users: Train staff to recognize and avoid actions that could lead to exploitation.

The Jenkins Gatling Plugin vulnerability (CVE-2025-5806 / SECURITY-3588) highlights the ongoing challenges of securing plugin ecosystems within automation platforms.

With no immediate fix available, organizations must rely on downgrading, strict access controls, and enhanced security practices to protect their environments.

Security teams should prioritize this advisory and prepare to implement patches as soon as they become available.

By staying informed and proactive, organizations can mitigate the risks posed by this high-severity XSS vulnerability and maintain the integrity of their CI/CD pipelines.

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