Improper Restriction of XML External Entity Reference
Apache Standard Taglibs before 1.2.3 allows remote attackers to execute arbitrary code or conduct external XML entity (XXE) attacks via a crafted XSLT extension in a (1) <x:parse> or (2) <x:transform> JSTL XML tag.
CWE-611 - Improper Restriction of XML External Entity Reference
Listed 4th in the 'OWASP Top Ten', XML External Entities (XXE) vulnerability allows attackers to provide an XML input that contains an external entity. When the XML is parsed, it can cause data extraction and manipulation, execution of commands, denial-of-service attacks, and server-side request forgery.