pyasn1 has quadratic-complexity denial of service in binary REAL decoding

Summary In pyasn1 0.6.4 and earlier, decoding a binary-encoded ASN.1 REAL with a large mantissa can consume CPU time quadratic in the mantissa length. The BER, CER, and DER decoders all use the affected RealPayloadDecoder. An application is exposed when it passes attacker-controlled ASN.1...