GHSA-xhg9-xwch-vr7x

### Impact

Cloudflare quiche was discovered to be vulnerable to unbounded storage of information related to connection ID retirement, which could lead to excessive resource consumption. Each QUIC connection possesses a set of connection Identifiers (IDs); see [RFC 9000 Section 5.1](https://datatracker.ietf.org/doc/html/rfc9000#section-5.1). Endpoints declare the number of active connection IDs they are willing to support using the active_connection_id_limit transport parameter. The peer can create new IDs using a NEW_CONNECTION_ID frame but must stay within the active ID limit. This is done by retirement of old IDs, the endpoint sends NEW_CONNECTION_ID includes a value in the retire_prior_to field, which elicits a RETIRE_CONNECTION_ID frame as confirmation. An unauthenticated remote attacker can exploit the vulnerability by sending NEW_CONNECTION_ID frames and manipulating the connection (e.g. by restricting the peer's congestion window size) so that RETIRE_CONNECTION_ID frames can only be sent at a slower rate than they are received, leading to storage of information related to connection IDs in an unbounded queue.

### Patches

Quiche versions 0.19.2 and 0.20.1 are the earliest to address this problem. There is no workaround for affected versions.