Skip to content

Harden EppXmlSanitizer against XXE and entity expansion #3117

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
CydeWeys merged 1 commit into from
Jun 30, 2026
Merged

Harden EppXmlSanitizer against XXE and entity expansion #3117

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions core/src/main/java/google/registry/xml/XmlTransformer.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,10 @@ public static XMLInputFactory createXmlInputFactory() {
// Prevent XXE attacks.
xmlInputFactory.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false);
xmlInputFactory.setProperty(XMLInputFactory.SUPPORT_DTD, false);
xmlInputFactory.setXMLResolver(
(publicID, systemID, baseURI, namespace) -> {
throw new XMLStreamException("Entity resolution disabled.");
});
return xmlInputFactory;
}

Expand Down
9 changes: 9 additions & 0 deletions core/src/test/java/google/registry/flows/EppXmlSanitizerTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -116,4 +116,13 @@ void testSanitize_utf16_encodingPreserved() {
String sanitizedXml = sanitizeEppXml(inputXml.getBytes(UTF_16LE));
assertThat(sanitizedXml).isEqualTo(inputXml);
}

@Test
void testSanitize_withDtd_returnsBase64() {
String inputXml = "<!DOCTYPE foo [<!ENTITY xxe SYSTEM \"file:///etc/passwd\">]><pw>&xxe;</pw>";
byte[] inputXmlBytes = inputXml.getBytes(UTF_8);
// Since DTDs are disabled, parsing should fail and fallback to base64 encoding of input.
String expectedBase64 = Base64.getMimeEncoder().encodeToString(inputXmlBytes);
assertThat(sanitizeEppXml(inputXmlBytes).trim()).isEqualTo(expectedBase64.trim());
}
}
Loading