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fix(core): HTML-encode form action in PostbackResult to prevent XSS #1653

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fix(core): HTML-encode form action in PostbackResult to prevent XSS #1653

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16 changes: 15 additions & 1 deletion core/src/main/java/org/apache/struts2/result/PostbackResult.java
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,8 @@

// Render
PrintWriter pw = new PrintWriter(response.getOutputStream());
pw.write("<!DOCTYPE html><html><body><form action=\"" + finalLocation + "\" method=\"POST\">");
String safeLocation = encodeHtml(finalLocation);
pw.write("<!DOCTYPE html><html><body><form action=\"" + safeLocation + "\" method=\"POST\">");

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Code scanning / CodeQL

Information exposure through an error message Medium

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can be exposed to an external user.
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can be exposed to an external user.

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Code scanning / CodeQL

Cross-site scripting Medium

Cross-site scripting vulnerability due to a
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.
writeFormElements(request, pw);
writePrologueScript(pw);
pw.write("</html>");
Expand Down Expand Up @@ -213,6 +214,19 @@
this.prependServletContext = prependServletContext;
}

/**
* Encodes special HTML characters to prevent injection in HTML attribute context.
*/
private static String encodeHtml(String value) {
if (value == null) {
return "";
}
return value.replace("&", "&amp;")
.replace("\"", "&quot;")
.replace("<", "&lt;")
.replace(">", "&gt;");
}

protected void writeFormElement(PrintWriter pw, String name, String[] values) throws UnsupportedEncodingException {
for (String value : values) {
String encName = URLEncoder.encode(name, StandardCharsets.UTF_8);
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