CVE-2025-30215: NATS Server may fail to authorize certain Jetstream admin APIs

nats-server did not include authorization checks on 4 separate admin-level JetStream APIs: account purge, server remove, account stream move, and account stream cancel-move.

In all cases, APIs are not properly restricted to system-account users. Instead, any authorized user can execute the APIs, including across account boundaries, as long as the current user merely has permission to publish on $JS.>.

Only the first seems to be of highest severity. All are included in this single report as they seem likely to have the same underlying root cause.

Reproduction of the ACCOUNT.PURGE case is below. The others are like it.