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CVE Record

CVE-2021-27097: The boot loader in Das U-Boot before 2021.04-rc2 mishandles a modified FIT.

The boot loader in Das U-Boot before 2021.04-rc2 mishandles a modified FIT.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This issue affects Das U-Boot before 2021.04-rc2 when handling a modified FIT boot image. If an attacker can get a vulnerable system to process such an image, the boot process could be compromised with high confidentiality, integrity, and availability impact.

Executive priority

Treat as a high-priority firmware governance issue for products or appliances using older U-Boot. It is not proven internet-exploited from the provided evidence, but compromise at bootloader level can undermine device trust and recovery.

Technical view

CVE-2021-27097 is a FIT image handling flaw in Das U-Boot before 2021.04-rc2. The CVSS vector is local, low complexity, no privileges, user interaction required, with high CIA impact. The source bundle does not provide lower-level root-cause details or a complete affected product matrix.

Likely exposure

Most relevant to embedded devices, appliances, or firmware environments using Das U-Boot before 2021.04-rc2 and FIT images. Exposure depends on whether attackers can influence boot media, firmware update images, recovery flows, or signed image handling.

Exploitation context

The CVE is not listed as KEV in the provided bundle, and no cited source states active exploitation. CVSS indicates local attack conditions and required user interaction, so risk is highest where boot images or update paths are weakly controlled.

Researcher notes

The public description is sparse: it names modified FIT mishandling and the fixed upstream boundary but not detailed mechanics. Avoid assuming specific device vendors. Focus validation on U-Boot version, FIT usage, update trust boundaries, and whether downstream firmware incorporated the referenced commits.

Mitigation direction

  • Inventory firmware and bootloader versions for Das U-Boot usage.
  • Prioritize vendor firmware or packages incorporating the upstream fixes.
  • Review the referenced Debian LTS advisory if using Debian packages.
  • Restrict who can supply boot media or firmware update images.
  • Check vendor guidance for platform-specific remediation details.

Validation and detection

  • Confirm whether affected assets use Das U-Boot before 2021.04-rc2.
  • Identify whether FIT images are used in boot or update workflows.
  • Verify installed firmware includes the referenced upstream fixes.
  • Review vendor or Debian package advisories for fixed build numbers.
  • Document devices where boot media access is physically or operationally exposed.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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

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CVE-2021-27097 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AC:L/AV:L/A:H/C:H/I:H/PR:N/S:U/UI:R1.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2021-27097Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.