CVE-2021-21574Public exploit

UEFI code execution via stack buffer overflow

Published Jun 24, 2021 · Updated Sep 16, 2024

Stack-based buffer overflow in Dell BIOSConnect allows local users with administrator privileges to execute code in the UEFI preboot environment. Public disclosures identify one of three independent overflows in OS-recovery or firmware-update content processing, but do not assign a specific parser or operation to this CVE. Exploitation requires local administrator access and preboot user interaction; successful code execution bypasses UEFI restrictions.

CVSS severity7.5
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Dell BIOSConnect allows local users with administrator privileges to execute code in the UEFI preboot environment. Public disclosures identify one of three independent overflows in OS-recovery or firmware-update content processing, but do not assign a specific parser or operation to this CVE. Exploitation requires local administrator access and preboot user interaction; successful code execution bypasses UEFI restrictions.

The record

CVE
CVE-2021-21574
Published
Jun 24, 2021
Updated
Sep 16, 2024
Vendor
Dell
Product
BIOSConnect
Classifications
CWE-121, CWE-787, T1542.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jun 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record 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=unspecified <Gen 11, Gen 10

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Dell · BIOSConnectversion=unspecified <Gen 11, Gen 10

Published CVSS scores

6.9NIST NVDAV:L/AC:M/Au:N/C:C/I:C/A:C
7.2DellCVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H
7.5NIST NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/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-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1542.001Pre-OS Boot System Firmware

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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