Potential Impacts of XXE Attacks

• Information Disclosure: Attackers can use XXE to retrieve files from the server, potentially exposing sensitive data like user credentials, financial information, or internal documents.

Example: An attacker might use XXE to access the file `/etc/passwd` on the server, 
which contains usernames and hashed passwords for all system users.

• Server-Side Request Forgery (SSRF): XXE attacks can be used to trick the server into making unauthorized requests to other internal systems or even external websites.

Example: An attacker might use XXE to force the server to send a request to an internal system 
that exposes user data or launch a denial-of-service attack against another website.

• Denial-of-Service (DoS): By crafting malicious XXE entities that consume excessive resources, attackers can overload the server and make it unavailable to legitimate users.

Example: An attacker might submit an XXE payload that forces the server to download 
a large file repeatedly, exhausting system resources and causing a DoS attack.

• Code Execution (Rare): In some cases, XXE vulnerabilities can be exploited to execute arbitrary code on the server, allowing attackers complete control over the system.

Example (Hypothetical): An attacker might exploit a specific vulnerability in the XML parser 
to inject code that gives them remote access to the server.

XML External Entity (XXE) processing vulnerabilities are security concerns in web applications that handle XML data. They arise when an application parses XML input containing references to external entities without proper validation.

These entities can point to external resources like files or URLs, and attackers can exploit them for malicious purposes.