The pyasn1 library used by gcalcli is vulnerable to a Denial of Service (DoS) 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 memory exhaustion, crashing the host application. This affects versions >=4.3.0 and <4.5.1_9. A fix is available in version 4.5.1_9.