XML entity expansion
Summary: XML entity expansion vulnerabilities arise because the XML specification lets documents define entities that reference other entities within the same document, and when this is done recursively to significant depth the parser consumes exponentially increasing memory and processor resources. The result can be a denial-of-service condition that stops the entire application from functioning, and Burp Suite verifies recursive expansion only to a modest depth to avoid causing an actual outage.
What's compelling: A single crafted XML document with deeply nested DOCTYPE entities can exhaust memory and CPU until the application stops serving anyone, and the fix depends on configuring your XML parser to disable DOCTYPE support or blocking that tag through input validation.
Read the original at PortSwigger Research ↗
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