Fix XML external entity processing in Java and Spring Boot
==========================================================

Configure the XML parser to refuse the DTD: in Java set the Apache feature
disallow-doctype-decl to true on the DocumentBuilderFactory, so any DOCTYPE is
a fatal error and no external entity (CWE-611) or entity expansion (CWE-776)
runs. Add the external-entity and secure-processing features as defence in
depth. Do not blocklist '<!DOCTYPE' in the bytes; a UTF-16 copy evades it.

Page: https://softwaresecurity.com/fix/xxe/java-spring/

What is in this archive
-----------------------
xxe/java-spring/   the project: three implementations of the same code and one test suite
  src/main/java/com/example/xxe/impl/VulnerableContactParser.java   (vulnerable)
  src/main/java/com/example/xxe/impl/FixedContactParser.java   (fixed)
  src/main/java/com/example/xxe/impl/WrongContactParser.java   (a plausible fix that still fails)
run-all.mjs   runs the tests in all three modes and checks the results (Node.js only)
LICENSE-CODE.txt

Run it
------
  Tested with OpenJDK 21.0.12.1 (Homebrew), Maven 3.9.16. run-all.mjs needs
  Node.js 22 or later. Supported versions:
  https://softwaresecurity.com/fix/versions/

  From the xxe/java-spring folder, install the dependencies once (this needs
  network access):

    mvn -B -q test

  Then run the tests. IMPL chooses the implementation the tests load:

    # every test passes
    IMPL=fixed mvn -B -o -q test
    # an exploit test fails
    IMPL=vulnerable mvn -B -o -q test
    # a test fails
    IMPL=wrong mvn -B -o -q test

  The JUnit report is written to target/surefire-reports/TEST-*.xml. To run all
  three modes and check the results in one step, run the harness from this top
  folder (it needs only Node.js; --install runs the install step first):

    node run-all.mjs --install xxe/java-spring
    node run-all.mjs xxe/java-spring

Verified
--------
  11 October 2026, with openjdk 21.0.12.1, maven 3.9.16, springBoot 4.1.1,
  junitJupiter 6.0.3. Versions and results hold for that date: run the tests
  with your own versions before relying on the fix.

Licence
-------
  The code is MIT licensed (LICENSE-CODE.txt). The page text is CC BY 4.0.
