CVE-2026-72711 Lean 4 before 4.32.2 Kernel Accepts Opaque Declaration With an Unbound Free Variable

The Lean 4 kernel does not check that the body of an opaque declaration is closed. environment::addopaque omits the checknometavarnofvar call that the definition and theorem paths perform, so a value containing a free variable that is absent from the local context is not rejected outright. A...