Semtech LR11xx Secure Boot Bypass

The Semtech LR11xx LoRa transceivers implement secure boot functionality using digital signatures to authenticate firmware. However, the implementation uses a non-standard cryptographic hashing algorithm that is vulnerable to second preimage attacks. An attacker with physical access to the device can exploit this weakness to generate a malicious firmware image with a hash collision, bypassing the secure boot verification mechanism and installing arbitrary unauthorized firmware on the device.