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CVE Record

CVE-2021-35951: fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows an Unauthenticated Remote attacker to send...

fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows an Unauthenticated Remote attacker to send a malicious firmware update via BLE and brick the device.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Fastrack Reflex 2.0 activity tracker firmware update process can reportedly accept malicious firmware over Bluetooth Low Energy without authentication, letting an attacker render the tracker unusable. The impact is device availability, not data theft, and sources do not report active exploitation or a confirmed vendor fix.

Executive priority

Treat this as a targeted device-availability risk, not an enterprise compromise risk. Prioritize inventory, user communication, and replacement planning if affected devices exist, especially where tracker availability matters operationally.

Technical view

CVE-2021-35951 affects Fastrack Reflex 2.0 W307S_REFLEX_v90.89. The reported issue is unauthenticated firmware update delivery via BLE, causing device bricking. CVSS 3.1 is 7.5 high with availability-only impact. The source bundle lists no CWE, no precise CPE, and no confirmed remediation.

Likely exposure

Exposure is limited to organizations or users operating Fastrack Reflex 2.0 trackers, especially firmware W307S_REFLEX_v90.89. Because the attack path is described as BLE, practical exposure likely depends on proximity and device state, although the CVE vector is listed as network.

Exploitation context

The bundle does not identify active exploitation, and the CVE is not marked as CISA KEV. Public information supports a denial-of-service outcome through malicious firmware update delivery, but does not provide evidence of broad exploitation or criminal use.

Researcher notes

Key gaps remain: affected metadata is incomplete, no CWE is assigned, and the bundle names no patch. The BLE update path and CVSS network vector should be reconciled against the original advisory before making exposure assumptions.

Mitigation direction

  • Inventory Fastrack Reflex 2.0 devices and identify firmware W307S_REFLEX_v90.89.
  • Check Fastrack and advisory sources for firmware, support, or replacement guidance.
  • Remove affected trackers from sensitive operational use until remediation is confirmed.
  • Limit unnecessary Bluetooth exposure and physical proximity to untrusted environments.
  • Replace unsupported affected devices if no vendor-supported remediation exists.

Validation and detection

  • Confirm whether any Fastrack Reflex 2.0 devices are in use.
  • Record model and firmware versions from device management or user inventory.
  • Review vendor and Payatu advisory information for affected version confirmation.
  • Check whether devices can receive vendor-approved firmware updates.
  • Document compensating controls or retirement decisions for affected trackers.
Prepared
Confidence
medium
Sources
4

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-2021-35951 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
7.5 (3.1)
Known Exploited
No
Published

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

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
3Source 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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2021-35951Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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.