# CVE-2021-34430: Weak cryptography in Eclipse TinyDTLS

> Remote attackers can decrypt DTLS traffic by computing the master key due to reliance on a weak C library random number generator.

- **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:** 8 Jul 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-ffg3-3xwj-f92r

## What is CVE-2021-34430?

CVE-2021-34430 is a high-severity vulnerability in The Eclipse Foundation Eclipse TinyDTLS, published on 8 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Eclipse TinyDTLS through 0.9-rc1 relies on the rand function in the C library, which makes it easier for remote attackers to compute the master key and then decrypt DTLS traffic.

Weakness: CWE-326 (Inadequate Encryption Strength), CWE-338 (Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG))

## Which versions are affected by CVE-2021-34430?

It affects 1 product.


Products: Eclipse Tinydtls.

## How do I fix CVE-2021-34430?

No fix has been published for CVE-2021-34430 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34430 being exploited?

There is no known exploitation of CVE-2021-34430 in the wild and no public exploit code.

## Other vulnerabilities in The Eclipse Foundation Eclipse TinyDTLS

- [CVE-2017-7243](https://insights.sbomify.com/CVE-2017-7243/): Null dereference in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34430 and fix it if it is affected.

What it is: CVE-2021-34430 is a high-severity vulnerability in The Eclipse Foundation Eclipse TinyDTLS, published on 8 Jul 2021. 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-2021-34430 in the wild and no public exploit code.

Affected product: The Eclipse Foundation Eclipse TinyDTLS. 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-2021-34430/ (Markdown: https://insights.sbomify.com/CVE-2021-34430/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34430
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34430
- OSV: https://osv.dev/vulnerability/CVE-2021-34430

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34430/
Summaries are generated and may contain mistakes; the official description above is the record.