Rollback protection is a security control that prevents a device from installing an older firmware or software version after a newer one has been accepted. It usually works by tracking version numbers, security patch levels, or cryptographic metadata and refusing updates that would downgrade the system. This stops attackers from replacing a patched image with one that still contains known vulnerabilities.
It matters because many attacks succeed by abusing trust in the update process. If a malicious actor can force a downgrade, they may re-enable bugs that were already fixed, bypass hardening, or gain a path to persistent compromise. In Android and embedded devices such as automotive head units, rollback protection complements verified boot and signature checks: authenticity alone is not enough if an older, signed build can be installed. Defenders use it to keep firmware updates one-way, while attackers try to bypass it by tampering with version counters, abusing recovery modes, or exploiting weak update logic.