CVE-2021-21555

Preboot code execution via heap buffer overflow

Published Jun 14, 2021 · Updated Sep 16, 2024

Heap-based buffer overflow in Dell PowerEdge BIOS before 2.11.2 allows local users to execute code, disclose data, or crash firmware. Dell locates the corruption in the UEFI or BIOS preboot environment but does not disclose the affected routine or malformed input operation. Exploitation requires high privileges, user interaction, and an affected PowerEdge system with NVDIMM-N installed; consequences are confined to preboot firmware execution, disclosure, or service interruption.

CVSS severity6.1
Medium
EPSS probability0.31%
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 PowerEdge BIOS before 2.11.2 allows local users to execute code, disclose data, or crash firmware. Dell locates the corruption in the UEFI or BIOS preboot environment but does not disclose the affected routine or malformed input operation. Exploitation requires high privileges, user interaction, and an affected PowerEdge system with NVDIMM-N installed; consequences are confined to preboot firmware execution, disclosure, or service interruption.

The record

CVE
CVE-2021-21555
Published
Jun 14, 2021
Updated
Sep 16, 2024
Vendor
Dell
Product
PowerEdge BIOS Intel 15G
Classifications
CWE-122
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jun 14, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <2.11.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Dell · PowerEdge BIOS Intel 15Gversion=unspecified <2.11.2

Published CVSS scores

7.2NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
6.1DellCVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:L
6.7NVDCVSS:3.1/AV:L/AC:L/PR:H/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.

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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-122Heap-based Buffer Overflow

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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