CVE-2021-3809Public exploit

Kernel-to-SMM privilege escalation via unsafe SMI callout

Published Jan 30, 2023 · Updated Mar 27, 2025

Improper privilege management in HP PC BIOS allows local users with kernel privileges to execute arbitrary code in System Management Mode. An SMI handler registered at code 0x63 calls EFI Boot Services LocateProtocol from SMM, allowing an attacker to overwrite its physical-memory function pointer and redirect execution. Exploitation requires kernel-level execution and the ability to trigger the software SMI; successful use grants firmware-level control beyond the operating system.

CVSS severity8.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege management in HP PC BIOS allows local users with kernel privileges to execute arbitrary code in System Management Mode. An SMI handler registered at code 0x63 calls EFI Boot Services LocateProtocol from SMM, allowing an attacker to overwrite its physical-memory function pointer and redirect execution. Exploitation requires kernel-level execution and the ability to trigger the software SMI; successful use grants firmware-level control beyond the operating system.

The record

CVE
CVE-2021-3809
Published
Jan 30, 2023
Updated
Mar 27, 2025
Vendor
Plantronics
Product
HP PC BIOS
Classifications
CWE-269, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jan 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=See HP Security Bulletin reference for affected versions.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Plantronics · HP PC BIOSversion=See HP Security Bulletin reference for affected versions.

Published CVSS scores

8.8HP Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-269Improper Privilege Management
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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