RUSTSEC-2026-0288 cosmian_kyber: AVX2 backend skips Fujisaki-Okamoto implicit rejection, enabling chosen-ciphertext key recovery

Summary cosmiankyber is a fork of Argyle-Software/kyber and inherits a broken constant-time conditional-move routine cmov in its AVX2 backend. When built with the opt-in avx2 feature on x8664, cmov is a no-op: it never performs the copy. That cmov is the step that applies the Fujisaki-Okamoto FO...

cosmian_kyber: AVX2 backend skips Fujisaki-Okamoto implicit rejection, enabling chosen-ciphertext key recovery

Summary cosmiankyber is a fork of Argyle-Software/kyber and inherits a broken constant-time conditional-move routine cmov in its AVX2 backend. When built with the opt-in avx2 feature on x8664, cmov is a no-op: it never performs the copy. That cmov is the step that applies the Fujisaki-Okamoto FO...