# CVE-2021-42146: Information disclosure in n/a

> Remote attackers can reuse DTLS epoch numbers to obtain sensitive application data from connected clients in Contiki-NG.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Jan 2024
- **Updated:** 20 Jun 2025
- **Also known as:** GHSA-wmpm-9r6p-rpww

## What is CVE-2021-42146?

CVE-2021-42146 is a high-severity vulnerability in n/a, published on 24 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers allow remote attackers to reuse the same epoch number within two times the TCP maximum segment lifetime, which is prohibited in RFC6347. This vulnerability allows remote attackers to obtain sensitive application (data of connected clients).

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-303 (Incorrect Implementation of Authentication Algorithm)

## Which versions are affected by CVE-2021-42146?

It affects 1 product.


Products: Contiki-Ng Tinydtls.

## How do I fix CVE-2021-42146?

No fix has been published for CVE-2021-42146 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-42146 being exploited?

There is no known exploitation of CVE-2021-42146 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-42143](https://insights.sbomify.com/CVE-2021-42143/): Denial of service in n/a (critical 9.1)
- [CVE-2021-42147](https://insights.sbomify.com/CVE-2021-42147/): Denial of service in n/a (critical 9.1)
- [CVE-2021-42142](https://insights.sbomify.com/CVE-2021-42142/): Denial of service in n/a (high 8.2)
- [CVE-2021-42145](https://insights.sbomify.com/CVE-2021-42145/): Denial of service in n/a (high 7.5)
- [CVE-2021-42141](https://insights.sbomify.com/CVE-2021-42141/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42146 and fix it if it is affected.

What it is: CVE-2021-42146 is a high-severity vulnerability in n/a, published on 24 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-42146 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-2021-42146/ (Markdown: https://insights.sbomify.com/CVE-2021-42146/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42146
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42146
- OSV: https://osv.dev/vulnerability/CVE-2021-42146

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42146/
Summaries are generated and may contain mistakes; the official description above is the record.