Riot Games Implements Strict Anti-Cheat Update That Could Sideline Older PCs
Riot Games has updated its Vanguard anti-cheat to close a critical "pre-boot" loophole. While this improves security, it requires a BIOS firmware update that many older motherboards no longer support, potentially blocking users from playing Valorant and League of Legends.
Riot Games has introduced a significant security update to its Vanguard anti-cheat system that may leave users with older hardware unable to play titles like Valorant and League of Legends. The update, which addresses a critical vulnerability in computer motherboards, requires players to have the latest BIOS firmware installed, a demand that some aging PCs simply cannot meet.
The "Pre-Boot" Vulnerability
In a security bulletin released on December 18, 2025, Riot Games revealed it had discovered a "critical flaw" affecting a wide range of motherboards. This vulnerability involves the Input-Output Memory Management Unit (IOMMU), a component designed to protect a computer's memory from unauthorized access during the boot process.
According to the developer, the flaw creates a "pre-boot gap" where the system reports that security features are active when they are essentially "asleep." This window allows sophisticated cheats to inject code before the Windows operating system, and the Vanguard anti-cheat software even loads, making the cheats nearly undetectable.
Why This Hurts Older PCs
To close this loophole, Vanguard now enforces stricter checks to ensure a user's motherboard firmware (BIOS) is patched against this specific UEFI flaw. As noted by Ars Technica, this presents a major hurdle for older systems. Many older motherboards, particularly those using older chipsets (such as early Intel 300-series or older AMD AM4 boards), may effectively have reached their "end of life" status. Manufacturers often stop releasing BIOS updates for hardware that is several years old.
If a motherboard manufacturer does not release a patch for a specific older model, the user's only option to continue playing may be to buy a new motherboard and CPU. Players on affected systems will encounter a VAN:Restriction error message preventing the game from launching, a move TechSpot describes as Riot "forcing Valorant players to update their PC firmware."
Impact on Players
Currently, Riot is rolling out these restrictions in phases. The requirement initially targets "certain players" whose system configurations look suspicious or similar to known cheaters. However, the studio has stated it considers expanding this requirement to all players in high-ranking competitive tiers (such as Ascendant, Immortal, and Radiant in Valorant) to ensure competitive integrity.
Riot acknowledges the friction this causes but maintains it is necessary. In their official statement, the company noted, "By closing this pre-boot loophole, we are neutralizing an entire class of previously untouchable cheats." Security experts at Bleeping Computer have confirmed that the flaw enables pre-boot attacks on motherboards from major vendors like Gigabyte, MSI, ASUS, and ASRock.
What You Should Do
If you are a Valorant or League of Legends player, you can take the following steps to ensure you aren't locked out:
- Check for Updates: Visit your motherboard manufacturer's website and download the latest BIOS/UEFI firmware update.
- Enable Security Features: Ensure that TPM 2.0, Secure Boot, and IOMMU are enabled in your BIOS settings.
- Monitor Vanguard Messages: If you receive a VAN:Restriction notification, follow the specific instructions provided by the client.
