Six U-Boot bootloader flaws could run code before a device checks its firmware

Researchers at Binarly found six flaws in U-Boot, the open-source bootloader inside routers, IoT devices, industrial systems, and the management chips of data-center servers. All six are triggered while U-Boot is still reading an untrusted firmware image, before it verifies the signature, so an attacker who supplies a malicious image can act before the trust check runs. Two of the flaws can lead to arbitrary code execution at boot, undermining the whole chain of trust, while the other four crash the device. The vulnerable code dates back to 2013, affecting many releases and vendor forks. Exploiting them does not always need physical access: a compromised management interface could push a malicious image.

Check

Identify devices built on U-Boot, especially servers with baseboard management controllers and networking or IoT gear, and check with vendors whether firmware updates addressing these flaws are available or planned.

Affected

Devices using U-Boot, including many routers, IoT and industrial systems, and server management controllers; malicious firmware images can crash them or run code at boot before the signature is verified.

Fix

Apply vendor firmware updates as they incorporate the upstream fixes, restrict and monitor access to management interfaces that can push firmware images, and retire devices no longer receiving updates.