Improper Restriction of XML External Entity Reference
The Upload add-on resource in Atlassian Universal Plugin Manager before version 2.22.14 allows remote attackers who have system administrator privileges to read files, make network requests and perform a denial of service attack via an XML External Entity vulnerability in the parsing of atlassian plugin xml files in an uploaded JAR.
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.