LangChain's XMLOutputParser vulnerable to XML Entity Expansion
The XMLOutputParser in LangChain uses the etree module from the XML parser in the standard python library which has some XML vulnerabilities; see: https://docs.python.org/3/library/xml.htmlThis primarily affects users that combine an LLM (or agent) with the `XMLOutputParser` and expose the component via an endpoint on a web-service.This would allow a malicious party to attempt to manipulate the LLM to produce a malicious payload for the parser that would compromise the availability of the service.A successful attack is predicated on:Usage of XMLOutputParserPassing of malicious input into the XMLOutputParser either directly or by trying to manipulate an LLM to do so on the users behalfExposing the component via a web-service