Multiple denial-of-service vulnerabilities exist in the python-pyasn1 library prior to version 0.6.5. These flaws involve quadratic CPU complexity during decoding of specially crafted ASN.1 BER, CER, or DER inputs with many fragments or colliding tag sets. An attacker can exploit these to exhaust CPU resources and reduce service availability without impacting confidentiality or integrity. The issues are fixed in version 0.6.5.