suspicious-xml-expat-reader-usage (S315)

Derived from the flake8-bandit linter.

What it does

Checks for uses of insecure XML parsers.

Why is this bad?

Many XML parsers are vulnerable to XML attacks (such as entity expansion), which cause excessive memory and CPU usage by exploiting recursion. An attacker could use such methods to access unauthorized resources.

Consider using the defusedxml package when parsing untrusted XML data, to protect against XML attacks.

Example

from xml.sax.expatreader import create_parser

parser = create_parser()

Use instead:

from defusedxml.sax import create_parser

parser = create_parser()

References

• Python documentation: xml — XML processing modules
• PyPI: defusedxml
• Common Weakness Enumeration: CWE-400
• Common Weakness Enumeration: CWE-776