CVE-2021-26410: AMD Secure Processor Info Disclosure Bug

CVE-2021-26410 Overview

CVE-2021-26410 is an improper syscall input validation vulnerability affecting the AMD Secure Processor (ASP). The flaw allows an attacker to force the kernel into reading syscall parameter values from its own memory space, enabling them to infer the contents of kernel memory and potentially disclose sensitive information.

Critical Impact

This vulnerability enables kernel memory information disclosure through improper syscall input validation in AMD Secure Processor, potentially exposing sensitive system data to attackers with local access.

Affected Products

• AMD Secure Processor (ASP) enabled systems
• AMD processors with vulnerable ASP firmware versions
• Systems requiring AMD security bulletin AMD-SB-4013 or AMD-SB-6024 updates

Discovery Timeline

• 2026-02-10 - CVE CVE-2021-26410 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2021-26410

Vulnerability Analysis

This vulnerability is classified under CWE-822 (Untrusted Pointer Dereference), indicating that the AMD Secure Processor fails to properly validate syscall input parameters before processing them. The improper validation allows an attacker to manipulate syscall parameters in a way that forces the kernel to read values from its own memory space rather than from the intended secure memory regions.

The attack requires local access with high privileges, and exploitation complexity is considered high. The vulnerability specifically impacts the confidentiality and integrity of the affected system at a low level, with no availability impact. While the vulnerability does not have confirmed public exploits available, the nature of the flaw could allow a sophisticated attacker to gradually infer kernel memory contents through careful manipulation of syscall parameters.

Root Cause

The root cause stems from inadequate input validation in the AMD Secure Processor's syscall handling mechanism. When processing system calls, the ASP fails to properly verify that the memory addresses and parameter values provided are within expected bounds and originate from authorized memory regions. This oversight allows crafted syscall parameters to redirect memory read operations to kernel memory space.

Attack Vector

The attack vector is local, requiring the attacker to have existing access to the target system with elevated privileges. The attacker would need to:

1. Gain local access to a system with a vulnerable AMD Secure Processor
2. Craft malicious syscall parameters designed to exploit the improper input validation
3. Issue specially crafted syscalls that manipulate the ASP into reading from kernel memory
4. Observe the system responses to infer kernel memory contents over time

This side-channel style attack could potentially expose sensitive information stored in kernel memory, including cryptographic keys, credentials, or other privileged data structures.

Detection Methods for CVE-2021-26410

Indicators of Compromise

• Unusual syscall patterns targeting AMD Secure Processor interfaces
• Abnormal memory access patterns detected in system call monitoring
• Elevated privilege processes making repeated syscalls with unusual parameters
• Unexpected kernel memory read operations from ASP-related processes

Detection Strategies

• Monitor system call activity for anomalous patterns targeting ASP interfaces
• Implement kernel-level auditing to detect unusual memory access patterns
• Deploy endpoint detection solutions capable of identifying side-channel attack behaviors
• Utilize AMD-specific security tools to verify ASP firmware integrity

Monitoring Recommendations

• Enable detailed syscall logging on systems with AMD Secure Processors
• Monitor for privilege escalation attempts preceding potential exploitation
• Implement memory access auditing for kernel space operations
• Review AMD security bulletins regularly for firmware update notifications

How to Mitigate CVE-2021-26410

Immediate Actions Required

• Review and apply AMD security bulletin AMD-SB-4013 updates
• Review and apply AMD security bulletin AMD-SB-6024 updates
• Update AMD Secure Processor firmware to the latest patched version
• Restrict local system access to authorized users only
• Implement the principle of least privilege for all system accounts

Patch Information

AMD has released security bulletins addressing this vulnerability. Administrators should consult the AMD Security Bulletin AMD-SB-4013 and AMD Security Bulletin AMD-SB-6024 for specific patch information, affected product lists, and firmware update instructions. System firmware updates should be applied according to AMD's guidance and tested in a non-production environment before deployment.

Workarounds

• Restrict local access to systems containing sensitive data until patches can be applied
• Implement additional access controls and monitoring for privileged operations
• Consider isolating systems with vulnerable AMD processors from sensitive workloads
• Enable enhanced system call monitoring to detect potential exploitation attempts