The pyasn1 library contains a denial of service vulnerability caused by unbounded recursion when decoding ASN.1 data with deeply nested indefinite-length SEQUENCE or SET tags. An attacker can supply a crafted payload that triggers recursive decoding calls without depth checks, leading to a RecursionError or out-of-memory crash. This vulnerability affects services parsing untrusted ASN.1 data, such as LDAP, SNMP, Kerberos, and X.509 parsers, allowing remote attackers to crash service workers with small payloads.