CVE-2020-10683 (https://nvd.nist.gov/vuln/detail/CVE-2020-10683): dom4j before 2.1.3 allows external DTDs and External Entities by default, which might enable XXE attacks. However, there is popular external documentation from OWASP showing how to enable the safe, non-default behavior in any application that uses dom4j.
*** This bug has been marked as a duplicate of bug 719318 ***