CVE-2021-21556

Name: CVE-2021-21556
Creator: NVD / NIST
Published: 2021-06-14T19:15:08.353+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.7/10EPSS 0.31%

Last modified Jun 17, 2026

CVE-2021-21556 is a medium-severity vulnerability rated 6.7/10 on the CVSS scale. Dell PowerEdge R640, R740, R740XD, R840, R940, R940xa, MX740c, MX840c, and T640 Server BIOS contain a stack-based buffer overflow vulnerability in systems with NVDIMM-N 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.. EPSS estimates a 0.31% chance of exploitation in the next 30 days.

Description

Dell PowerEdge R640, R740, R740XD, R840, R940, R940xa, MX740c, MX840c, and T640 Server BIOS contain a stack-based buffer overflow vulnerability in systems with NVDIMM-N 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.

Metrics

CVSS 3.1

6.7/10

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.31%

22.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Dell	Poweredge R640 Firmware	< 2.11.2
Dell	Poweredge R740 Firmware	< 2.11.2
Dell	Poweredge R740xd Firmware	< 2.11.2
Dell	Poweredge R940 Firmware	< 2.11.2
Dell	Poweredge R840 Firmware	< 2.11.2
Dell	Poweredge R940xa Firmware	< 2.11.2
Dell	Poweredge T640 Firmware	< 2.11.2
Dell	Poweredge Mx740c Firmware	< 2.11.2
Dell	Poweredge Mx840c Firmware	< 2.11.2

References

https://www.dell.com/support/kbdoc/000187958Vendor Advisory
https://www.dell.com/support/kbdoc/000187958Vendor Advisory

Timeline

Published: Jun 14, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21556?

How severe is CVE-2021-21556?

CVE-2021-21556 has a CVSS score of 6.7/10 (MEDIUM severity). The EPSS model estimates a 0.31% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21556?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21556?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST