U-Boot and old Secure Boot shims expose a long-lived firmware trust problem

Researchers disclosed six vulnerabilities in U-Boot and separately showed that 11 Microsoft-signed UEFI shim bootloaders can still undermine Secure Boot. These boot-chain problems matter because they allow attackers to execute code before the operating system starts, which makes detection and removal far harder than normal malware. The shim issue is particularly notable because the signed loaders were old, trusted by Microsoft, and still broadly present on many systems even after revocation efforts. The U-Boot bugs affect embedded hardware, routers, cameras, and other devices that run much of the internet's infrastructure. This matters because boot-chain weaknesses can create persistent compromise paths that survive disk wipes and conventional endpoint protection. The combined reports show that firmware and bootloader security remain a critical blind spot for both consumer and enterprise hardware.

Sources

• Critical U-Boot Bugs Undermine Secure Boot on Millions of Devices — Security Affairs
• 6 U-Boot Vulnerabilities Let Attackers Hijack Boot Process — Vulnerability – InfoTech News
• No one knows how many old shims can still bypass UEFI Secure Boot — Help Net Security
• 11 Old Signed UEFI Shims Just Broke Secure Boot on Millions of PCs — Latest Hacking News