The python-pyasn1 library, used for ASN.1 data decoding in Python, contains multiple vulnerabilities prior to version 0.6.5 that cause excessive CPU consumption during decoding of attacker-controlled inputs. These issues arise from quadratic-time operations when processing certain ASN.1 types such as schemaless containers, constructed strings, BIT STRINGs, and binary REAL values. Exploitation can lead to CPU exhaustion and reduced service availability without impacting confidentiality or integrity. The vulnerabilities are fixed in version 0.6.5.