Security Vulnerability - Action Required: XXE vulnerability in the newest version of the tutorials

[Yiheng Cao]

I think the module xml may be vulnerable to Improper Restriction of XML External Entity Reference. It shares similarities to a recent CVE disclosure CVE-2021-3878 and CVE-2021-3869 in the project stanfordnlp/CoreNLP. The vulnerable methods are as follows:

1. com.baeldung.xml.JaxenDemo.getAllTutorial() in the file xml/src/main/java/com/baeldung/xml/JaxenDemo.java.
2. com.baeldung.xml.DefaultParser.getFirstLevelNodeList() in the file xml/src/main/java/com/baeldung/xml/DefaultParser.java
3. com.baeldung.xml.DefaultParser.getNodeById(String id) in the file xml/src/main/java/com/baeldung/xml/DefaultParser.java
4. com.baeldung.xml.DefaultParser.getNodeListByTitle(String name) in the file xml/src/main/java/com/baeldung/xml/DefaultParser.java.

The source vulnerability information is as follows:

Vulnerability Detail:
CVE Identifier: CVE-2021-3878 and CVE-2021-3869
Description: corenlp is vulnerable to Improper Restriction of XML External Entity Reference
Reference:https://nvd.nist.gov/vuln/detail/CVE-2021-3869 for CVE-2021-3869 and https://nvd.nist.gov/vuln/detail/CVE-2021-3878 for CVE-2021-3878.
Patch: stanfordnlp/CoreNLP@5d83f1e for CVE-2021-3869 and stanfordnlp/CoreNLP@e5bbe13 for CVE-2021-3878.

Vulnerability Description:
This vulnerability occurs because of the Improper Restriction of XML External Entity Reference. Given that the XML schema files which is compromised by a hacker, the victim conducts regular process may result in an XML External Entity (XXE) Injection attack.

Recommended Actions:
The corresponding fixes are similar to CVE-2021-3878 and CVE-2021-3869 to some extent. I have provided the following fixes by applying several patching statements, ensuring that the external entities and DTDs are not loaded when parsing and processing XML documents using the document builder. You can call the function safeDocumentBuilderFactory I defined below instead of directly calling DocumentBuilderFactory.newInstance() to create a DocumentBuilderFactory object to avoid XXE attacks.

  public static DocumentBuilderFactory safeDocumentBuilderFactory() {
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
      dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
      dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
      dbf.setFeature("http://xml.org/sax/features/external-general-entities", false);
      dbf.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
      dbf.setFeature("http://apache.org/xml/features/dom/create-entity-ref-nodes", false);
      dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
    } catch (ParserConfigurationException e) {
      log.warn(e);
    }
    return dbf;
  }

Considering the potential riskes it may have, I am willing to cooperate with your to verify, address, and report the identified vulnerability promptly through responsible means. If you require any further information or assistance, please do not hesitate to reach out to me.
Thank you and looking forward to hearing from you soon.

[Ulisses Lima]

Hey, @Crispy-fried-chicken.

Thanks for bringing this to our attention. We'll look into this.

This issue will remain open until then.