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Directory traversal vulnerability while serving static content
Who should read this
All Struts 2 developers
Impact of vulnerability
Read access to server filesystem resources (under certain application server environments)
Maximum security rating
Developers should upgrade to Struts 2.0.12
Struts 2.0.0 - Struts 184.108.40.206
Original JIRA Ticket
Csaba Barta and László Tóth, PricewaterhouseCoopers
The Struts2 dispatcher logic by design allows to serve certain static resources found in the classpath of the web application for request URIs having a context relative path starting with "/struts/".
FilterDispatcher (in 2.0) and DefaultStaticContentLoader (in 2.1) have a security vulnerability that allows an attacker to traverse the directory structure and download files outside the "static" content folder, using double-encoded urls and relative paths, like:
Although not all container are vulnerable to this, the Struts2 dispatcher logic has to prevent access to static content outside the static resource folders.
As of Struts 2.0.12, the dispatcher logic was improved to correctly decode and normalize the request path before checking if static content serving applies for a given request.
You can obtain Struts 2.0.12 as a drop in replacement for Struts 220.127.116.11 to get the fixed Struts 2 core library.