CVE-2021-26383
📋 TL;DR
CVE-2021-26383 is a memory corruption vulnerability in AMD's Trusted Execution Environment (TEE) where insufficient bounds checking allows attackers with compromised userspace to execute commands with malformed arguments, leading to out-of-bounds memory access. This affects systems with AMD processors that have TEE enabled, potentially compromising system integrity or availability.
💻 Affected Systems
- AMD EPYC 7002 Series Processors
- AMD EPYC 7003 Series Processors
- AMD Ryzen PRO 4000 Series Processors
- AMD Ryzen 5000 Series Processors with Radeon Graphics
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through arbitrary code execution in the trusted execution environment, potentially bypassing security boundaries and gaining elevated privileges.
Likely Case
System crash or denial of service through memory corruption, potentially leading to data corruption in the TEE environment.
If Mitigated
Limited impact if TEE is disabled or proper access controls prevent userspace compromise, though availability could still be affected.
🎯 Exploit Status
Exploitation requires prior compromise of userspace and knowledge of TEE command interfaces. No public exploits have been documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AMD AGESA firmware updates: ComboAM4v2PI 1.2.0.3c, ComboAM4v2PI 1.2.0.5, and later versions
Vendor Advisory: https://www.amd.com/en/resources/product-security/bulletin/AMD-SB-4012.html
Restart Required: Yes
Instructions:
1. Check current BIOS/UEFI firmware version. 2. Download appropriate firmware update from motherboard/system manufacturer. 3. Apply firmware update following manufacturer instructions. 4. Reboot system to activate new firmware.
🔧 Temporary Workarounds
Disable AMD TEE
allDisable the Trusted Execution Environment in BIOS/UEFI settings to remove the vulnerable component
Restrict Userspace Access
allImplement strict access controls to prevent unauthorized userspace execution
🧯 If You Can't Patch
- Disable AMD TEE in BIOS/UEFI settings if not required for operations
- Implement network segmentation and strict access controls to limit exposure
🔍 How to Verify
Check if Vulnerable:
Check BIOS/UEFI firmware version against AMD's advisory. On Linux: 'sudo dmidecode -t bios' or check /sys/class/dmi/id/bios_versionCheck Version:
On Linux: 'sudo dmidecode -t bios | grep Version' or 'cat /sys/class/dmi/id/bios_version'Verify Fix Applied:
Verify firmware version has been updated to patched version. Check that AMD TEE is functioning properly if required.📡 Detection & Monitoring
Log Indicators:
- Unexpected system crashes or reboots
- Kernel panic logs related to memory corruption
- TEE service failures
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
EventID: 41 (Windows) OR kernel: panic (Linux) combined with system model containing affected AMD processors