An XML External Entity (XXE) attack specifically targets weaknesses in a service's parser when handling a data format structured for remote communications. By taking advantage of this, an attacker could attempt to craft data that defines or references external entities, which the parser may erroneously process, resulting in data leakage or server-side request forgery (SSRF). Conversely, a buffer overflow attack is less about exploiting the data handling in a parser and more about overwhelming memory buffers. Directory traversal aims to access files and directories that are stored outside the web root folder, which is not directly related to the weak parser issue. Cross-Site Scripting (XSS) is primarily a web application vulnerability that allows injection of scripts into web pages viewed by other users and doesn't typically target service parsers handling remote procedure calls.