CVE-2021-0091

Q: What is the severity of CVE-2021-0091?

CVE-2021-0091 has a CVSS score of 7.8 (HIGH). This vulnerability allows an unauthenticated attacker with local access to improperly access firmware controls in certain Intel processors, potentially enabling privilege escalation. It affects systems running vulnerable Intel processor firmware versions.

7.8 HIGH

📋 TL;DR

This vulnerability allows an unauthenticated attacker with local access to improperly access firmware controls in certain Intel processors, potentially enabling privilege escalation. It affects systems running vulnerable Intel processor firmware versions.

💻 Affected Systems

Products:

Intel Processors with vulnerable firmware

Versions: Specific firmware versions as listed in Intel advisory

Operating Systems: All operating systems running on affected processors

Default Config Vulnerable: ⚠️ Yes

Notes: Requires physical or remote local access to the system. Virtual machines may also be affected if running on vulnerable hardware.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

An attacker gains full system control by escalating privileges from a low-privileged user to kernel or firmware-level access.

🟠

Likely Case

Local attackers could bypass security controls to access restricted system resources or data.

🟢

If Mitigated

With proper access controls and firmware updates, the attack surface is significantly reduced.

🌐 Internet-Facing: LOW - Requires local access to the system.

🏢 Internal Only: HIGH - Local attackers on shared systems or compromised accounts could exploit this.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires local access and knowledge of firmware interfaces. No public exploits have been documented.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firmware updates provided by Intel and system manufacturers

Vendor Advisory: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00527.html

Restart Required: Yes

Instructions:

1. Check Intel advisory for affected processors. 2. Contact system manufacturer for firmware updates. 3. Apply firmware update following manufacturer instructions. 4. Reboot system to activate new firmware.

🔧 Temporary Workarounds

Restrict Local Access

all

Limit physical and remote local access to systems with vulnerable firmware

Implement Least Privilege

all

Ensure users have minimal necessary privileges to reduce impact of escalation

🧯 If You Can't Patch

Isolate affected systems from untrusted networks and users
Implement strict access controls and monitoring for local privilege escalation attempts

🔍 How to Verify

Check if Vulnerable:

Check system BIOS/UEFI firmware version against Intel's advisory list

Check Version:

On Linux: sudo dmidecode -t bios | grep Version; On Windows: wmic bios get smbiosbiosversion

Verify Fix Applied:

Verify firmware version has been updated to patched version from manufacturer

📡 Detection & Monitoring

Log Indicators:

Unusual firmware access attempts
Privilege escalation events
BIOS/UEFI configuration changes

Network Indicators:

Local network traffic indicating privilege escalation attempts

SIEM Query:

EventID=4672 OR EventID=4688 on Windows systems showing privilege changes

📊 Metadata

CVE ID: CVE-2021-0091

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published: February 9, 2022

Last Updated: May 5, 2025

🔗 References

https://security.netapp.com/advisory/ntap-20220210-0007/ Third Party Advisory
https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00527.html Vendor Advisory
https://security.netapp.com/advisory/ntap-20220210-0007/ Third Party Advisory
https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00527.html Vendor Advisory

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Atom C3308 by Intel

Atom C3336 by Intel

Atom C3338 by Intel

Atom C3338r by Intel

Atom C3436l by Intel

Atom C3508 by Intel

Atom C3538 by Intel

Atom C3558 by Intel

Atom C3558r by Intel

Atom C3708 by Intel

Atom C3750 by Intel

Atom C3758 by Intel

Atom C3758r by Intel

Atom C3808 by Intel

Atom C3830 by Intel

Atom C3850 by Intel

Atom C3858 by Intel

Atom C3950 by Intel

Atom C3955 by Intel

Atom C3958 by Intel

Cloud Backup by Netapp

Core I3 1000g1 by Intel

Core I3 1000g4 by Intel

Core I3 1005g1 by Intel

Core I3 10100 by Intel

Core I3 10100e by Intel

Core I3 10100f by Intel

Core I3 10100t by Intel

Core I3 10100te by Intel

Core I3 10100y by Intel

Core I3 10105 by Intel

Core I3 10105f by Intel

Core I3 10105t by Intel

Core I3 10110u by Intel

Core I3 10110y by Intel

Core I3 10300 by Intel

Core I3 10300t by Intel

Core I3 10305 by Intel

Core I3 10305t by Intel

Core I3 10320 by Intel

Core I3 10325 by Intel

Core I3 11100he by Intel

Core I3 1110g4 by Intel

Core I3 1115g4 by Intel

Core I3 1115g4e by Intel

Core I3 1115gre by Intel

Core I3 1120g4 by Intel

Core I3 1125g4 by Intel

Core I3 6006u by Intel

Core I3 6098p by Intel

Core I3 6100 by Intel

Core I3 6100e by Intel

Core I3 6100h by Intel

Core I3 6100t by Intel

Core I3 6100te by Intel

Core I3 6100u by Intel

Core I3 6102e by Intel

Core I3 6157u by Intel

Core I3 6167u by Intel

Core I3 6300 by Intel

Core I3 6300t by Intel

Core I3 6320 by Intel

Core I3 7020u by Intel

Core I3 7100 by Intel

Core I3 7100e by Intel

Core I3 7100h by Intel

Core I3 7100t by Intel

Core I3 7100u by Intel

Core I3 7101e by Intel

Core I3 7101te by Intel

Core I3 7102e by Intel

Core I3 7130u by Intel

Core I3 7167u by Intel

Core I3 7300 by Intel

Core I3 7300t by Intel

Core I3 7320 by Intel

Core I3 7350k by Intel