CVE-2021-21571

Dell UEFI BIOS https stack leveraged by the Dell BIOSConnect feature and Dell HTTPS Boot feature...

5.9 Medium

Dell UEFI BIOS https stack leveraged by the Dell BIOSConnect feature and Dell HTTPS Boot feature contains an improper certificate validation vulnerability. A remote unauthenticated attacker may exploit this vulnerability using a person-in-the-middle attack which may lead to a denial of service and payload tampering.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: None
Integrity: Low
Availability: High

Exploit likelihood

0.54%Down 0.1 points since Jun 25, 2021

What each source reports

CVE List Score used 5.9

Record: CVE-2021-21571
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
Weakness: CWE-295
Updated: 2026-11-02

EUVDEUVD-2021-8843 5.9

Record: EUVD-2021-8843
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
Updated: 2026-11-03

GitHub AdvisoriesGHSA-g784-x97g-r6ww No score

Dell UEFI BIOS https stack leveraged by the Dell BIOSConnect feature and Dell HTTPS Boot feature...

Record: GHSA-g784-x97g-r6ww
Weakness: CWE-295
Updated: 2026-11-02

NVD 5.9

Record: CVE-2021-21571
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
CVSS 2.0: 5.8 MediumAV:N/AC:M/Au:N/C:N/I:P/A:P
Weakness: CWE-295
Updated: 2026-11-02

Affected products

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History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases, published	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-21571 is a medium vulnerability (CVSS 5.9) in Dell Uefi Bios Https Stack, published June 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.54%, the 45th percentile. No source names a fixed version.