Nordic Semiconductor nRF52840 devices through 2020-10-19 have improper protection against physical side channels. The flash read-out protection (APPROTECT) can be bypassed by injecting a fault during the boot phase.

The elliptic curve cryptography (ECC) hardware accelerator, part of the ARM® TrustZone® CryptoCell 310, contained in the NordicSemiconductor nRF52840 through 2021-03-29 has a non-constant time ECDSA implemenation. This allows an adversary to recover the private ECC key used during an ECDSA operation.