CVE-2021-21572

UEFI code execution via heap buffer overflow

Published Jun 24, 2021 · Updated Sep 16, 2024

Heap-based buffer overflow in Dell BIOSConnect allows local administrators to execute arbitrary code in the UEFI environment. Dell and the public researcher disclosure do not identify which BIOSConnect recovery or firmware-update parser writes downloaded content beyond a heap buffer. Exploitation requires local administrator access, high complexity, and user interaction; successful code execution bypasses UEFI restrictions.

CVSS severity7.2
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Dell BIOSConnect allows local administrators to execute arbitrary code in the UEFI environment. Dell and the public researcher disclosure do not identify which BIOSConnect recovery or firmware-update parser writes downloaded content beyond a heap buffer. Exploitation requires local administrator access, high complexity, and user interaction; successful code execution bypasses UEFI restrictions.

The record

CVE
CVE-2021-21572
Published
Jun 24, 2021
Updated
Sep 16, 2024
Vendor
Dell
Product
BIOSConnect
Classifications
CWE-787, CWE-122, 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

7.2DellCVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H
7.5NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
6.9NVDAV:L/AC:M/Au:N/C:C/I:C/A:C

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-122Heap-based Buffer Overflow
T1542.001Pre-OS Boot: System Firmware

Public exploit references

No public exploit references are available in this record.

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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