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  • S2-028
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Use of a JRE with broken URLDecoder implementation may lead to XSS vulnerability in Struts 2 based web applications.

Who should read this

All Struts 2 developers and users

Impact of vulnerability

Affects of a cross-site scripting vulnerability.

Maximum security rating



Upgrade runtime JRE to a recent major version, preferably 1.8. Alternatively upgrade to Struts 2.3.28

Affected Software

Struts 2.0.0 - Struts Struts


WhiteHat Security (

CVE Identifier



When using a single byte page encoding such as ISO-8895-1, an attacker might submit a non-spec URL-encoded parameter value including multi-byte characters.

Struts 2 used the standard JRE URLDecoder to decode parameter values. Especially JRE 1.5's URLDecoder implementation seems to be broken to the point that this non-spec encoding isn't rejected / filtered. In later JREs the issue was fixed, best known solution is found in JRE 1.8.


Upgrade runtime JRE/JDK, preferably to the most recent 1.8 version.

Alternatively upgrade to Struts 2.3.28, which includes and uses a safe URLDecoder implementation from Apache Tomcat

Backward compatibility

No issues expected when upgrading to Struts 2.3.28


Use UTF-8 for page and parameter encoding.

Further Reference

WW-4507 - Struts 2 XSS vulnerability with <s:textfield> Closed

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