# CVE-2021-35954: Security feature bypass in n/a

> Physically proximate attackers can dump firmware, flash malicious code, or brick the device via the Serial Wire Debug interface.

- **Severity:** High 8.1 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Dec 2022
- **Updated:** 14 Apr 2025
- **Also known as:** GHSA-wh39-w6w2-hmvf

## What is CVE-2021-35954?

CVE-2021-35954 is a high-severity vulnerability in n/a, published on 26 Dec 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows physically proximate attackers to dump the firmware, flash custom malicious firmware, and brick the device via the Serial Wire Debug (SWD) feature.

## Which versions are affected by CVE-2021-35954?

It affects 1 product.


Products: Fastrack Reflex 2.0 Firmware.

## How do I fix CVE-2021-35954?

No fix has been published for CVE-2021-35954 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-35954 being exploited?

There is no known exploitation of CVE-2021-35954 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-35951](https://insights.sbomify.com/CVE-2021-35951/): fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows an Unauthenticated Remote attacker to send a malicious firmware update via B (high 7.5)
- [CVE-2021-35953](https://insights.sbomify.com/CVE-2021-35953/): fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows a Remote attacker to cause a Denial of Service (device outage) via crafted c (high 7.5)
- [CVE-2021-35952](https://insights.sbomify.com/CVE-2021-35952/): fastrack Reflex 2.0 W307S_REFLEX_v90.89 Activity Tracker allows a Remote attacker to change the time, date, and month via Bluetooth LE Chara (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-35954 and fix it if it is affected.

What it is: CVE-2021-35954 is a high-severity vulnerability in n/a, published on 26 Dec 2022. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-35954 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-35954/ (Markdown: https://insights.sbomify.com/CVE-2021-35954/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-35954
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-35954
- OSV: https://osv.dev/vulnerability/CVE-2021-35954

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-35954/
Summaries are generated and may contain mistakes; the official description above is the record.