CVE-2021-21554

Dell PowerEdge R640, R740, R740XD, R840, R940, R940xa, MX740c, MX840c, and, Dell Precision 7920 Rack Workstation BIOS contain a stack-based buffer overflow vulnerability in systems with Intel Optane DC Persistent Memory installed. A local malicious user with high privileges may potentially exploit this vulnerability, leading to a denial of Service, arbitrary code execution, or information disclosure in UEFI or BIOS Preboot Environment.

Published: 2021-06-14 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21554 is rated Low Risk (33.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.34%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-21554

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.34% +0.29%
2 2025-03-30 0.10% 0.05% -0.05%
3 2025-03-29 — 0.10% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21554

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:L Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 0.6 5.5 [email protected]
6.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.8 5.9 [email protected]
7.2 2.0 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.9 10.0 [email protected]

Weakness enumeration for CVE-2021-21554

Affected software / configurations for CVE-2021-21554

Vendor Product Version Raw CPE
dell poweredge_r640_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r640_firmware:*:*:*:*:*:*:*:*
dell poweredge_r740_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r740_firmware:*:*:*:*:*:*:*:*
dell poweredge_r740xd_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r740xd_firmware:*:*:*:*:*:*:*:*
dell poweredge_r940_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r940_firmware:*:*:*:*:*:*:*:*
dell poweredge_r840_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r840_firmware:*:*:*:*:*:*:*:*
dell poweredge_r940xa_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_r940xa_firmware:*:*:*:*:*:*:*:*
dell poweredge_mx740c_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_mx740c_firmware:*:*:*:*:*:*:*:*
dell poweredge_mx840c_firmware < 2.9.4 cpe:2.3:o:dell:poweredge_mx840c_firmware:*:*:*:*:*:*:*:*
dell precision_7920_firmware — cpe:2.3:o:dell:precision_7920_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-21554

URL Tags
https://www.dell.com/support/kbdoc/000187958 Patch Vendor Advisory
cvelogic Threat Intelligence