Jenkins 2.227 and earlier, LTS 2.204.5 and earlier served files uploaded as file parameters to a build without specifying appropriate Content-Security-Policy HTTP headers. This resulted in a stored cross-site scripting (XSS) vulnerability exploitable by users with permissions to build a job with file parameters.\n\nJenkins now sets Content-Security-Policy HTTP headers when serving files uploaded via a file parameter to the same value as used for files in workspaces and archived artifacts not served using the Resource Root URL.\n\nThe system property hudson.model.DirectoryBrowserSupport.CSP can be set to override the value of Content-Security-Policy headers sent when serving these files. This is the same system property used for files in workspaces and archived artifacts unless those are served via the Resource Root URL and works the same way for file parameters. See Configuring Content Security Policy to learn more.\n\nEven when Jenkins is configured to serve files in workspaces and archived artifacts using the Resource Root URL (introduced in Jenkins 2.200), file parameters are not, and therefore still subject to Content-Security-Policy restrictions.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-2162
• https://jenkins.io/security/advisory/2020-03-25/#SECURITY-1793
• http://www.openwall.com/lists/oss-security/2020/03/25/2
• jenkinsci/jenkins@c2d22b2