CVE-2026-72705: Rocq guard checker accepts fixpoint passed as higher-order argument (0 = 1 demonstrated)

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Posted by Jonathan Brossard on Oct 25 1. Summary ========== A soundness bug in the Rocq (formerly Coq) kernel s guard checker allows construction of a checked proof of False — and by extension, any proposition, including 0 = 1 — without axioms, tactics, plugins, or unsafe flags. Print Assumptions reports the proof as closed under the global context. The guard checker does not track recursive calls made through a fixpoint s own arguments. A fixpoint can pass itself to...