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Disable external entity resolution in XXE Challenge One's XML parser #261

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Disable external entity resolution in XXE Challenge One's XML parser #261

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80bbd22
Disable external entity resolution in XXE Challenge One's XML parser
JBHook Aug 9, 2026
351d2ec
Fix XXE in the XXE intro lesson's XML parser
JBHook Aug 9, 2026
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5 changes: 4 additions & 1 deletion src/main/java/servlets/module/challenge/XxeChallenge1OldWebService.java
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Original file line number Diff line number Diff line change
Expand Up @@ -130,8 +130,11 @@ public static String readXml(InputStream xmlEmail) {
Document doc;
String result;

// XmlDocumentBuilder.xmlDocBuilder's own parameter comments document the safe value for
// each flag - this call was passing the unsafe value for every single one, leaving external
// entity/DTD resolution fully enabled and open to XXE-based file disclosure.
DocumentBuilder dBuilder =
XmlDocumentBuilder.xmlDocBuilder(false, true, true, true, true, true);
XmlDocumentBuilder.xmlDocBuilder(true, false, false, false, false, false);
InputSource is = new InputSource(xmlEmail);

try {
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6 changes: 5 additions & 1 deletion src/main/java/servlets/module/lesson/XxeLesson.java
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Original file line number Diff line number Diff line change
Expand Up @@ -139,8 +139,12 @@ public static String readXml(InputStream xmlEmail) {
Document doc;
String result;

// XmlDocumentBuilder.xmlDocBuilder's own parameter comments document the safe value for
// each flag - this call was passing the unsafe value for every single one, leaving external
// entity/DTD resolution fully enabled and open to XXE-based file disclosure, same as the
// matching call already fixed in XxeChallenge1OldWebService.
DocumentBuilder dBuilder =
XmlDocumentBuilder.xmlDocBuilder(false, true, true, true, true, true);
XmlDocumentBuilder.xmlDocBuilder(true, false, false, false, false, false);
InputSource is = new InputSource(xmlEmail);

try {
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