An issue was discovered on OnePlus One, X, 2, 3, and 3T devices. OxygenOS and HydrogenOS are vulnerable to downgrade attacks. This is due to a lenient 'updater-script' in OTAs that does not check that the current version is lower than or equal to the given image's. Downgrades can occur even on locked bootloaders and without triggering a factory reset, allowing for exploitation of now-patched vulnerabilities with access to user data. This vulnerability can be exploited by a Man-in-the-Middle (MiTM) attacker targeting the update process. This is possible because the update transaction does not occur over TLS (CVE-2016-10370). In addition, a physical attacker can reboot the phone into recovery, and then use 'adb sideload' to push the OTA (on OnePlus 3/3T 'Secure Start-up' must be off).

An issue was discovered on OnePlus devices such as the 3T. The OnePlus OTA Updater pushes the signed-OTA image over HTTP without TLS. While it does not allow for installation of arbitrary OTAs (due to the digital signature), it unnecessarily increases the attack surface, and allows for remote exploitation of other vulnerabilities such as CVE-2017-5948, CVE-2017-8850, and CVE-2017-8851.