Security readout for executives and security teams
Plain-English summary
This Dell UEFI BIOS issue weakens certificate checking in HTTPS-based recovery or boot features. An attacker positioned between the device and Dell/network services could interfere with traffic, potentially causing denial of service or tampering with payloads. The attack is not reported as actively exploited in the supplied sources.
Executive priority
Treat this as a moderate firmware supply-chain exposure. It is not KEV-listed, but boot and recovery trust paths matter; prioritize affected Dell fleets that use BIOSConnect or HTTPS Boot on untrusted networks.
Technical view
CVE-2021-21571 is CWE-295 improper certificate validation in the Dell UEFI BIOS HTTPS stack used by BIOSConnect and HTTPS Boot. The CVSS 3.1 score is 5.9 with network attack vector, high complexity, no privileges, user interaction required, low integrity impact, and high availability impact.
Likely exposure
Exposure is limited to Dell environments using affected Gen 10 or Gen 11 UEFI BIOS HTTPS stack functionality, especially BIOSConnect or HTTPS Boot, where an attacker could achieve a person-in-the-middle position.
Exploitation context
The source describes remote unauthenticated exploitation through a person-in-the-middle attack. It does not cite public exploitation, CISA KEV listing, exploit availability, or confirmed in-the-wild attacks.
Researcher notes
Evidence is limited to the CVE record and Dell advisory reference. Do not assume broader Dell products, active exploitation, or specific fixes beyond Dell guidance. The key condition is attacker ability to intercept HTTPS traffic during relevant firmware workflows.
Mitigation direction
- Review Dell advisory 000188682 for affected models and vendor remediation guidance.
- Update affected BIOS or firmware only where Dell identifies an applicable update path.
- Assess whether BIOSConnect or HTTPS Boot are enabled and operationally required.
- Prioritize network controls that reduce person-in-the-middle opportunities during recovery or boot workflows.
Validation and detection
- Inventory Dell systems that rely on Gen 10 or Gen 11 UEFI BIOS HTTPS stack features.
- Confirm BIOSConnect and HTTPS Boot usage in firmware configuration or fleet management records.
- Compare installed BIOS versions against Dell advisory guidance for each affected model.
- Document systems where vendor guidance is unavailable or evidence is incomplete.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-295: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-21571 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H1.64.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.dell.com/support/kbdoc/en-us/000188682CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Certificate Validation
Improper Certificate Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.