Apache Struts 2 Documentation > Home > Security Bulletins > S2-002
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Summary

Cross site scripting (XSS) vulnerability on <s:url> and <s:a> tags

Who should read this All Struts 2 developers
Impact of vulnerability Injection of malicious client side code
Maximum security rating Important
Recommendation Developers using Struts 2 tags should immediately upgrade to Struts 2.0.11.1
Affected Software Struts 2.0.0 - Struts 2.0.11
Original JIRA Tickets WW-2414,WW-2427

Problem

For both the <s:url> and the <s:a> tag, it is possible to inject parameter values that do not get escaped properly when the tag's resulting URLs are constructed and rendered. The following scenarios are known:

  • A parameter value included in the construction of a <s:a> result can inject an unescaped double quote, thus being able to inject code in the resulting HTML by escaping the rendered href attribute.
  • Both the <s:url> and the <s:a> tag fail to escape <script> tags when includeParams is set to any other value than "none", which can be exploited by calling the containing JSP/action with GET parameters such as http://localhost/foo/bar.action?<script>alert(1)</script>test=hello

Solution

As of Struts 2.0.11.1

  • Double quotes do get escaped for parameter values used to constuct the output of a <s:a> tag
  • <script> tokens do get recursively escaped for parameter values used to contruct the output of <s:a> and <s:url> tags

You can obtain Struts 2.0.11.1 as a drop in replacement for Struts 2.0.11 to get the fixed Struts 2 core library.