E-fuses are commonly used to prevent downgrade attacks, where a system that only boots signed content can be tricked in to booting older versions with known vul

E-fuses are commonly used to prevent downgrade attacks, where a system that only boots signed content can be tricked in to booting older versions with known vulnerabilities that can then be chained in to a full exploit. Many of us first encountered them on the Xbox 360, where their use is documented in detail here: https://free60.org/Hardware/Fusesets/ https://free60.org/Hardware/Fusesets/ The short version is a signed firmware can be programmed to not boot if more than X amount of fuses are burned, so when a change occurs that the vendor wants to ensure can't be downgraded they just increase that number and burn fuses as part of the update process. Older versions fail the check and crash themselves. There is a hardware modification that can be done to prevent fuses from being burnt but that obviously has to be done before the update.