A stack-based buffer overflow in mangle_to_hex_lower() and mangle_to_hex_upper() in src/rp_cpu.c in hashcat v7.1.2 allows an attacker to cause a denial of service or possibly execute arbitrary code via a crafted rule file, or via the -j or -k rule options used with password candidates of 128 or more characters. The vulnerability is caused by a bounds check that fails to account for the 2x expansion that occurs when password bytes are converted to hexadecimal.