CVE-2021-3809

Q: What is the severity of CVE-2021-3809?

CVE-2021-3809 has a CVSS score of 7.8 (HIGH). This CVE describes vulnerabilities in HP PC BIOS/UEFI firmware that could allow attackers to execute arbitrary code with high privileges. Affected systems include certain HP PC products running vulnerable firmware versions. Successful exploitation could compromise system integrity at the firmware level.

7.8 HIGH

📋 TL;DR

This CVE describes vulnerabilities in HP PC BIOS/UEFI firmware that could allow attackers to execute arbitrary code with high privileges. Affected systems include certain HP PC products running vulnerable firmware versions. Successful exploitation could compromise system integrity at the firmware level.

💻 Affected Systems

Products:

Certain HP PC products (specific models listed in HP advisory)

Versions: Vulnerable BIOS/UEFI firmware versions prior to HP's security update

Operating Systems: All operating systems running on affected hardware

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerability exists at firmware level, independent of operating system

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise with persistent firmware-level malware that survives OS reinstallation and disk replacement

🟠

Likely Case

Local privilege escalation allowing attackers to bypass security controls and maintain persistence

🟢

If Mitigated

Limited impact with proper firmware updates and secure boot enabled

🌐 Internet-Facing: LOW

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation typically requires physical access or administrative privileges

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: HP BIOS/UEFI firmware updates with security fixes

Vendor Advisory: https://support.hp.com/us-en/document/ish_6184733-6184761-16/hpsbhf03788

Restart Required: Yes

Instructions:

1. Identify affected HP PC models using HP advisory. 2. Download latest BIOS/UEFI firmware from HP Support. 3. Run firmware update utility. 4. Restart system to complete installation.

🔧 Temporary Workarounds

Enable Secure Boot

all

Secure Boot helps prevent unauthorized firmware/software from loading during boot process

Physical Security Controls

all

Restrict physical access to prevent local exploitation

🧯 If You Can't Patch

Isolate affected systems from high-risk networks
Implement strict access controls and monitoring for physical access

🔍 How to Verify

Check if Vulnerable:

Check BIOS/UEFI firmware version against HP's advisory for affected versions

Check Version:

Windows: wmic bios get smbiosbiosversion | Linux: sudo dmidecode -s bios-version

Verify Fix Applied:

Verify BIOS/UEFI firmware version matches or exceeds patched version from HP advisory

📡 Detection & Monitoring

Log Indicators:

Unexpected BIOS/UEFI firmware modification events
Failed firmware update attempts

Network Indicators:

Unusual firmware update traffic from unauthorized sources

SIEM Query:

EventID=12 OR EventID=13 (System events for firmware changes) OR suspicious firmware update patterns

📊 Metadata

CVE ID: CVE-2021-3809

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

CWE: CWE-269

Published: February 1, 2023

Last Updated: March 27, 2025

🔗 References

https://support.hp.com/us-en/document/ish_6184733-6184761-16/hpsbhf03788 Vendor Advisory
https://support.hp.com/us-en/document/ish_6184733-6184761-16/hpsbhf03788 Vendor Advisory

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Elite Dragonfly Firmware by Hp

Elite Slice Firmware by Hp

Elite Slice G2 Firmware by Hp

Elite X2 1012 G2 Firmware by Hp

Elite X2 1013 G3 Firmware by Hp

Elite X2 G4 Firmware by Hp

Elitebook 1040 G4 Firmware by Hp

Elitebook 1050 G1 Firmware by Hp

Elitebook 725 G4 Firmware by Hp

Elitebook 735 G5 Firmware by Hp

Elitebook 735 G6 Firmware by Hp

Elitebook 745 G4 Firmware by Hp

Elitebook 745 G5 Firmware by Hp

Elitebook 745 G6 Firmware by Hp

Elitebook 755 G4 Firmware by Hp

Elitebook 755 G5 Firmware by Hp

Elitebook 820 G4 Firmware by Hp

Elitebook 828 G4 Firmware by Hp

Elitebook 830 G5 Firmware by Hp

Elitebook 830 G6 Firmware by Hp

Elitebook 836 G5 Firmware by Hp

Elitebook 836 G6 Firmware by Hp

Elitebook 840 G4 Firmware by Hp

Elitebook 840 G5 Firmware by Hp

Elitebook 840 G6 Firmware by Hp

Elitebook 840r G4 Firmware by Hp

Elitebook 846 G5 Firmware by Hp

Elitebook 848 G4 Firmware by Hp

Elitebook 850 G4 Firmware by Hp

Elitebook 850 G5 Firmware by Hp

Elitebook 850 G6 Firmware by Hp

Elitebook X360 1020 G2 Firmware by Hp

Elitebook X360 1030 G2 Firmware by Hp

Elitebook X360 1030 G3 Firmware by Hp

Elitebook X360 1030 G4 Firmware by Hp

Elitebook X360 1040 G5 Firmware by Hp

Elitebook X360 1040 G6 Firmware by Hp

Elitebook X360 830 G5 Firmware by Hp

Elitebook X360 830 G6 Firmware by Hp

Elitedesk 705 G3 Desktop Mini Pc Firmware by Hp

Elitedesk 705 G3 Microtower Pc Firmware by Hp

Elitedesk 705 G3 Small Form Factor Pc Firmware by Hp

Elitedesk 705 G4 Desktop Mini Pc Firmware by Hp

Elitedesk 705 G4 Microtower Pc Firmware by Hp

Elitedesk 705 G4 Small Form Factor Pc Firmware by Hp

Elitedesk 705 G4 Workstation Firmware by Hp

Elitedesk 705 G5 Desktop Mini Pc Firmware by Hp

Elitedesk 705 G5 Small Form Factor Pc Firmware by Hp

Elitedesk 800 35w G3 Desktop Mini Pc Firmware by Hp

Elitedesk 800 35w G4 Desktop Mini Pc Firmware by Hp

Elitedesk 800 65w G3 Desktop Mini Pc Firmware by Hp

Elitedesk 800 65w G4 Desktop Mini Pc Firmware by Hp

Elitedesk 800 95w G4 Desktop Mini Pc Firmware by Hp

Elitedesk 800 G3 Small Form Factor Pc Firmware by Hp

Elitedesk 800 G3 Tower Pc Firmware by Hp

Elitedesk 800 G4 Small Form Factor Pc Firmware by Hp

Elitedesk 800 G4 Tower Pc Firmware by Hp

Elitedesk 800 G4 Workstation Firmware by Hp

Elitedesk 800 G5 Desktop Mini Pc Firmware by Hp

Elitedesk 800 G5 Small Form Factor Pc Firmware by Hp

Elitedesk 800 G5 Tower Pc Firmware by Hp

Elitedesk 880 G3 Tower Pc Firmware by Hp

Elitedesk 880 G4 Tower Pc Firmware by Hp

Elitedesk 880 G5 Tower Pc Firmware by Hp

Eliteone 1000 G1 23.8 In All In One Business Pc Firmware by Hp

Eliteone 1000 G2 23.8 In All In One Business Pc Firmware by Hp

Eliteone 800 G3 23.8 Non Touch All In One Business Pc Firmware by Hp

Eliteone 800 G4 23.8 In All In One Business Pc Firmware by Hp

Eliteone 800 G5 23.8 In All In One Firmware by Hp

Engage Flex Pro C Retail System Firmware by Hp

Engage Flex Pro Retail System Firmware by Hp

Engage Go 10 Mobile System Firmware by Hp

Engage Go Mobile System Firmware by Hp

Engage One Aio System Firmware by Hp

Hp Mt21 Mobile Thin Client Firmware by Hp

Hp Mt31 Mobile Thin Client Firmware by Hp

Hp Mt44 Mobile Thin Client Firmware by Hp