title: DOS via an XML vulnerability in  XMLOutputParser
description: 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.html
This 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:
1. Usage of XMLOutputParser
2. Passing of malicious input into the XMLOutputParser either directly or by trying to manipulate an LLM to do so on the users behalf
3. Exposing the component via a web-service
problem types: CWE-776 Improper Restriction of Recursive Entity References in DTDs
affected:
{
vendor: langchain-ai
product: langchain-ai/langchain
versions:
version: unspecified, status: affected, versionType: custom, lessThanOrEqual: latest
}
metrics:
cvssV3_0: [
version: 3.0
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
baseScore: 5.9
baseSeverity: MEDIUM
]