A vulnerability in quinn-proto allows a client to retain an excessively long Retry token from a Retry packet without length limits, causing memory exhaustion or panic in the QUIC client. This occurs because the token is included in every Initial packet header, leading to an invalid packet size calculation. The issue affects all quinn-proto clients making outgoing connections. The flaw is fixed in version 0.11.19 by closing connections with PROTOCOL_VIOLATION when tokens leave insufficient room for frames.