CVE-2026-50185 RustCrypto Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set

RustCrypto CMOV provides conditional move CPU intrinsics which are guaranteed on major platforms to execute in constant-time and not be rewritten as branches by the compiler. From 0.1.1 until 0.5.4, the aarch64 implementations of Cmov and CmovEq in cmov/src/backends/aarch64.rs assume high bits ar...