Riot Games – yes, the one behind League of Legends and Valorant – has announced its findings on a new security flaw on some motherboards that allows cheaters to inject code whilst evading detections from the system, which means it could potentially render Riot’s very own Vanguard kernel anti-cheat ineffective, as well as virtually any other existing solution out there.
According To Riot, It’s The IOMMU Bug
Allow us to explain what that combinations of five alphabets even mean. IOMMU stands for Input-Output Memory Management Unit, and it’s a motherboard security feature that checks whether the ID of the devices (like PCIe cards) plugged into the system are in the whitelist. If not, the device simply isn’t allowed to communicate directly to the system RAM, which it usually does by bypassing the CPU and the operating system.
The bug in question here involves the timing of IOMMU initialization upon system boot, which some motherboards incorrectly signaled the system that it has been initialized despite a brief period of not being such in the earliest part of the boot sequence. This tiny window is all cheaters needed to slip the code into the system undetected, and the false positive result will get passed to the operating system, incorrectly determining that its security features are active and functional.
At least four brands are affected, which includes ASUS, GIGABYTE, MSI, and ASRock. The majority of the affected models are Intel-based platforms, whereas for AMD platforms, only GIGABYTE’s models are involved. Here’s the list of affected lineups:
| Brand | Affected Chipset Models |
|---|---|
| ASUS | Intel Z490, W480, B460, H410, Z590, B560, H510, Z690, B660, W680, Z790, B760, W790 |
| GIGABYTE | Intel Z690, Q670, B660, H610, W790, Z790, B760, Z890, W880, Q870, B860, H810 AMD X670, B650, A620, A620A, X870E, X870, B850, B840, TRX50* *TRX50 BIOS available in Q1 2026 |
| MSI | Intel 600, 700 series |
| ASRock | Intel 500, 600, 700, 800 series |
Riot says this bug can not only neutralize its Vanguard anti-cheat, the same thing can happen to all other anti-cheat systems as virtually all of them operate on the level that simply couldn’t see what the UEFI firmware is doing. Even for a kernel-level solution like Vanguard – which has been controversial due to its highly invasive nature – it can only monitor the operating system, so a hardware-level cheat involving modified DMA (direct memory access) hardware is not something that any anti-cheat can easily detect.
The developer will also be rolling out extra security checks for specific players, non-conforming systems will be given a prompt to let the user know if BIOS updates are needed. It noted that this requirement may only apply to high-ranking players (in the case of Valorant, that means anyone at Ascendant rank or above) to better ensure top-level players are using genuine hardware to achieve the result.
Pokdepinion: Pretty unusual to see a game developer doing the security researching.
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