CVE-2026-43859: mutt IMAP认证绕过漏洞

import hashlib # Simulate the vulnerable strfcpy behavior (simplified) def vulnerable_strfcpy(dest, src, size): # strfcpy copies 'size-1' bytes and ensures null termination # It stops at the first null byte in src i = 0 while i < size - 1 and i < len(src): if src[i] == 0: # Stop at null byte break dest[i] = src[i] i += 1 dest[i] = 0 # Null terminate return dest # Assume we have a dummy MD5 digest that contains a NULL byte at index 5 # Normal MD5 is 16 bytes. # In a real attack, the attacker (controlling the server) forces a challenge # that results in a specific digest from the client's known password. md5_digest = bytes([1, 2, 3, 4, 5, 0, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]) print(f"Original MD5 Digest (hex): {md5_digest.hex()}") # Vulnerable Code Execution buffer_size = 16 vuln_buffer = bytearray(buffer_size) copied_data = vulnerable_strfcpy(vuln_buffer, md5_digest, buffer_size) print(f"Vulnerable Copy (hex): {copied_data.hex()}") print("Note: Data truncated at the NULL byte (index 5). Authentication bypass possible if server accepts truncated hash.")