Package Instance

Cross-Site Request Forgery in Jenkins
An extension point in Jenkins allows selectively disabling cross-site request forgery (CSRF) protection for specific URLs.

Implementations of that extension point received a different representation of the URL path than the Stapler web framework uses to dispatch requests in Jenkins 2.227 and earlier, LTS 2.204.5 and earlier. This discrepancy allowed attackers to craft URLs that would bypass the CSRF protection of any target URL.

Jenkins now uses the same representation of the URL path to decide whether CSRF protection is needed for a given URL as the Stapler web framework uses.

In case of problems, administrators can disable this security fix by setting the system property `hudson.security.csrf.CrumbFilter.UNPROCESSED_PATHINFO` to `true`.

As an additional safeguard, semicolon (`;`) characters in the path part of a URL are now banned by default. Administrators can disable this protection by setting the system property `jenkins.security.SuspiciousRequestFilter.allowSemicolonsInPath` to `true`.

Improper Neutralization of Input During Web Page Generation in Jenkins
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](https://www.jenkins.io/doc/upgrade-guide/2.204/#resource-domain-support) and works the same way for file parameters. See [Configuring Content Security Policy](https://www.jenkins.io/doc/book/security/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.