CVE-2021-46755 : What You Need to Know

CVE-2021-46755 is a vulnerability that affects various AMD processor products, potentially leading to denial of service attacks due to a flaw in the AMD Secure Processor bootloader.

Understanding CVE-2021-46755

This vulnerability arises from an issue in unmapping certain SysHub mappings during error paths of the AMD Secure Processor bootloader.

What is CVE-2021-46755?

The failure to properly unmap SysHub mappings in the bootloader's error paths may enable a malicious bootloader to deplete SysHub resources, potentially causing a denial of service.

The Impact of CVE-2021-46755

This vulnerability could be exploited by an attacker to exhaust system resources, leading to a denial of service condition on affected AMD processor systems.

Technical Details of CVE-2021-46755

CVE-2021-46755 affects various AMD processor products using the AGESA package on x86 platforms.

Vulnerability Description

The vulnerability allows attackers with a malicious bootloader to exhaust SysHub resources, potentially leading to denial of service scenarios.

Affected Systems and Versions

Ryzen™ 3000 Series Desktop Processors “Matisse” AM4
AMD Ryzen™ 5000 Series Desktop Processors “Vermeer” AM4
Ryzen™ 5000 Series Desktop processor with Radeon™ Graphics “Cezanne” AM4
3rd Gen AMD Ryzen™ Threadripper™ Processors “Castle Peak” HEDT
Ryzen™ Threadripper™ PRO Processors “Castle Peak” WS
Ryzen™ Threadripper™ PRO Processors “Chagall” WS
Ryzen™ 3000 Series Mobile Processors with Radeon™ Graphics “Renoir”
Ryzen™ 5000 Series Mobile Processors with Radeon™ Graphics “Lucienne”
Ryzen™ 5000 Series Mobile processors with Radeon™ Graphics “Cezanne”

Exploitation Mechanism

The vulnerability can be exploited by attackers with a malicious bootloader, leveraging error paths in the ASP bootloader to exhaust SysHub resources.

Mitigation and Prevention

It is crucial to take immediate action to mitigate the risk posed by CVE-2021-46755.

Immediate Steps to Take

Apply patches or updates provided by AMD to address the vulnerability
Monitor system resources for unusual depletion or denial of service signs
Implement secure bootloader practices to prevent unauthorized access

Long-Term Security Practices

Regularly update firmware and processor software to patch known vulnerabilities
Conduct periodic security assessments to identify and address potential weaknesses in system components
Educate system users on best practices to mitigate security risks

Patching and Updates

AMD has released patches and updates to address CVE-2021-46755. It is essential to promptly apply these updates to ensure system security.