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escape scope attribute names and values in DumpTag #4316

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11 changes: 9 additions & 2 deletions log4j-taglib/src/main/java/org/apache/logging/log4j/taglib/DumpTag.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
import javax.servlet.jsp.tagext.TagSupport;
import org.apache.logging.log4j.util.StringBuilders;

/**
* This class implements the {@code <log:dump>} tag.
Expand Down Expand Up @@ -60,8 +61,8 @@ public int doEndTag() throws JspException {
final String name = names.nextElement();
final Object value = this.pageContext.getAttribute(name, this.scope);

this.pageContext.getOut().write("<dt><code>" + name + "</code></dt>");
this.pageContext.getOut().write("<dd><code>" + value + "</code></dd>");
this.pageContext.getOut().write("<dt><code>" + escapeHtml(name) + "</code></dt>");
this.pageContext.getOut().write("<dd><code>" + escapeHtml(String.valueOf(value)) + "</code></dd>");
}
this.pageContext.getOut().write("</dl>");
} catch (final IOException e) {
Expand All @@ -70,4 +71,10 @@ public int doEndTag() throws JspException {

return Tag.EVAL_PAGE;
}

private static String escapeHtml(final String value) {
final StringBuilder builder = new StringBuilder(value);
StringBuilders.escapeXml(builder, 0);
return builder.toString();
}
}
17 changes: 17 additions & 0 deletions log4j-taglib/src/test/java/org/apache/logging/log4j/taglib/DumpTagTest.java
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Expand Up @@ -88,6 +88,23 @@ void testDoEndTagDefaultPageScope() throws Exception {
"The output is not correct.");
}

@Test
void testDoEndTagEscapesHtml() throws Exception {
this.context.setAttribute("<name>", "<script>alert('xss')</script>", PageContext.PAGE_SCOPE);

final int returnValue = this.tag.doEndTag();
assertEquals(Tag.EVAL_PAGE, returnValue, "The return value is not correct.");

this.writer.flush();
final String output = new String(this.output.toByteArray(), UTF8);
assertEquals(
"<dl>" + "<dt><code>&lt;name&gt;</code></dt>"
+ "<dd><code>&lt;script&gt;alert(&apos;xss&apos;)&lt;/script&gt;</code></dd>"
+ "</dl>",
output,
"Attribute names and values must be HTML-escaped.");
}

@Test
void testDoEndTagSessionScopeNoAttributes() throws Exception {
this.context.setAttribute("badAttribute01", "skippedValue01", PageContext.PAGE_SCOPE);
Expand Down
12 changes: 12 additions & 0 deletions src/changelog/.2.x.x/fix_taglib_dump_tag_xss.xml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="https://logging.apache.org/xml/ns"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
https://logging.apache.org/xml/ns
https://logging.apache.org/xml/ns/log4j-changelog-0.xsd"
type="fixed">
<issue id="4316" link="https://github.com/apache/logging-log4j2/pull/4316"/>
<description format="asciidoc">
HTML-escape scope attribute names and values rendered by the `log:dump` JSP tag (`DumpTag`) to prevent cross-site scripting
</description>
</entry>
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