Apache Airflow HashiCorp provider: HashiCorp Vault secrets backend: team-scope guard bypass via user-controlled key

Apache Airflow HashiCorp provider: the HashiCorp Vault secrets backend's team-scope guard can be bypassed with a user-controlled key. In a multi-team deployment, a Dag author scoped to one team can supply a Variable key containing a path separator that causes the backend to resolve a secret belonging to a different team, because after the team-scoped lookup misses the backend falls back to a team-agnostic path concatenated from the unvalidated key. The Execution API Variables route accepts a path-shaped key, so this is reachable from ordinary Dag code. Affects multi-team deployments using the HashiCorp Vault secrets backend. Single-team deployments are not affected, as there is no cross-team boundary to cross. This is the same class as CVE-2026-86465, CVE-2026-68870, CVE-2026-68871 and CVE-2026-68872 in the Akeyless, Azure Key Vault, Yandex Lockbox and Amazon secrets backends. Users of apache-airflow-providers-hashicorp are recommended to upgrade to version 4.8.0 or later, which fixes the issue.