Recent ColorOS builds for new OnePlus flagships introduce a strict hardware-backed Anti-Rollback Protection (ARB) mechanism that can effectively block downgrades and severely restrict the installation of older custom ROMs. According to reports from the modding community, attempting to revert to a previous firmware after installing these updates can in many cases lead to a fully bricked device.
What Anti-Rollback Protection Is and How It Works in ColorOS
Anti-Rollback Protection is part of the Android Verified Boot (AVB) architecture, formally documented by Google in the Android Open Source Project. AVB validates the integrity and authenticity of the system partition on every boot, ensuring that the operating system has not been tampered with.
Within AVB, ARB adds an additional control: the system stores a rollback index (a security version counter) in tamper-resistant storage. Each official firmware image declares its own security level. On boot, the bootloader compares the firmware’s rollback index to the value stored in hardware. If the image has a lower security level than the one already recorded, the boot sequence is blocked.
The security objective is clear: prevent attackers from downgrading a device to a vulnerable firmware where known exploits exist. Google and several major vendors, including Xiaomi and Pixel devices, already rely on this model. It reduces the attack surface, but it also restricts legitimate downgrades and advanced modifications that depend on older builds.
e‑Fuse and Rollback Index: Why Downgrades Become Irreversible
In ColorOS versions 16.0.3.500 / 16.0.3.501 / 16.0.3.503, based on Android 16 for the latest OnePlus models, the vendor reportedly uses an e‑fuse–based implementation of ARB. An e‑fuse is a one‑time programmable hardware fuse embedded in the SoC or mainboard. When a new firmware with a higher rollback index is installed, the corresponding fuse state is irreversibly changed to store that security level.
After this fuse is “burned” to a new value, the bootloader will refuse to load any firmware whose rollback index is lower than the stored value. Because the e‑fuse cannot be reset by software, this change is permanent. Neither factory resets, fastboot flashing, service tools, nor official repair utilities can revert the rollback index.
The only theoretical way to bypass this hardware state would be a mainboard replacement, which from a practical standpoint makes the device’s trust chain non-downgradable. This is conceptually similar to the Samsung Knox warranty fuse, which trips on certain modifications, but with one critical difference: in the Samsung ecosystem, Knox typically disables features and warranty support, yet does not usually hard brick the device. On affected OnePlus devices, a failed downgrade after ARB activation can result in a device that no longer boots at all.
OnePlus and OPPO Devices Affected by the New ARB Mechanism
Based on current reports, the hardware Anti-Rollback Protection in ColorOS has already been enabled on at least the following models:
• OnePlus 13
• OnePlus 13T
• OnePlus 15
• OnePlus Ace 5 series
The OPPO Find X8 line is considered likely to receive the same protection, either already active in current firmware or planned for upcoming releases. In addition, future ColorOS updates for OnePlus 11 and OnePlus 12 are expected to enable similar ARB behavior.
At the moment, ARB has been observed in ColorOS builds, but ColorOS and OxygenOS share a largely common codebase. From a security lifecycle perspective, it is reasonable to assume that global OxygenOS firmware will eventually inherit comparable anti-rollback safeguards.
Impact on Custom ROMs, Rooting and the Modding Community
For everyday users who never unlock the bootloader or flash custom ROMs, this move primarily represents a security hardening step: it becomes significantly more difficult for malware or physical attackers to install an older, vulnerable firmware image.
For power users and developers, however, the consequences are substantial:
• Downgrading to an earlier official build after ARB activation can permanently brick the device.
• Installing custom ROMs based on older firmware or vendor trees with a lower rollback index carries a high risk of irreversible failure.
• Standard recovery paths (fastboot, recovery mode, vendor restore tools) may no longer function if they rely on images that the bootloader now considers “too old”.
Similar scenarios were observed when Xiaomi introduced ARB in certain MIUI versions: community reports documented devices that became unrecoverable without board-level repairs after users manually downgraded or flashed incompatible ROMs. The same risk profile now appears on recent OnePlus and OPPO hardware running new ColorOS builds.
Security Best Practices and Update Strategy for OnePlus and OPPO Owners
Users who value bootloader unlocking, root access, Magisk modules, or custom ROMs should approach upcoming firmware updates with caution. Prior to installing any ColorOS build suspected of enabling hardware ARB, it is advisable to:
• Avoid updating to ColorOS versions 16.0.3.500 / .501 / .503 without understanding the rollback implications for your exact model.
• Create full backups of user data and, where still technically possible, a snapshot of the current firmware and partitions.
• Monitor technical forums and developer communities (such as XDA, GitHub issues, and specialized Telegram channels) for confirmed ARB behavior on your device.
• Assume that once ARB is triggered, safe downgrades and many legacy custom ROMs will no longer be an option.
For the broader Android ecosystem, OnePlus and OPPO’s move is part of a clear trend: vendors are increasingly using hardware security primitives to enforce update integrity and limit downgrade vectors. This is beneficial for large-scale mobile cybersecurity, but it demands a more deliberate strategy from enthusiasts. Before updating, users should weigh the long-term trade‑off between maximum security and openness to modification, and treat each major firmware upgrade as a one‑way step in the device’s security lifecycle.
