Requests to the ConcatServlet and WelcomeFilter are able to access protected resources within the WEB-INF directory. For example a request to the ConcatServlet with a URI of /concat?/%2557EB-INF/web.xml can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.
This occurs because both ConcatServlet and WelcomeFilter decode the supplied path to verify it is not within the WEB-INF or META-INF directories. It then uses this decoded path to call RequestDispatcher which will also do decoding of the path. This double decoding allows paths with a doubly encoded WEB-INF to bypass this security check.
Impact
This affects all versions of ConcatServlet and WelcomeFilter in versions before 9.4.41, 10.0.3 and 11.0.3.
Workarounds
If you cannot update to the latest version of Jetty, you can instead deploy your own version of the ConcatServlet and/or the WelcomeFilter by using the code from the latest version of Jetty.
stevenseeley Analyst
Requests to the
ConcatServletandWelcomeFilterare able to access protected resources within theWEB-INFdirectory. For example a request to theConcatServletwith a URI of/concat?/%2557EB-INF/web.xmlcan retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.This occurs because both
ConcatServletandWelcomeFilterdecode the supplied path to verify it is not within theWEB-INForMETA-INFdirectories. It then uses this decoded path to callRequestDispatcherwhich will also do decoding of the path. This double decoding allows paths with a doubly encodedWEB-INFto bypass this security check.Impact
This affects all versions of
ConcatServletandWelcomeFilterin versions before 9.4.41, 10.0.3 and 11.0.3.Workarounds
If you cannot update to the latest version of Jetty, you can instead deploy your own version of the
ConcatServletand/or theWelcomeFilterby using the code from the latest version of Jetty.