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

> Attackers can cause denial of service in Mercurius GraphQL adapter by sending malformed WebSocket packets to the subscription endpoint.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Jan 2023
- **Updated:** 10 Mar 2025
- **Also known as:** GHSA-cm8h-q92v-xcfc

## What is CVE-2023-22477?

CVE-2023-22477 is a medium-severity denial of service vulnerability in mercurius-js mercurius, published on 9 Jan 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2023-22477?

4 open source packages ship an affected version, including mercurius. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mercurius` | npm | All versions | 8.13.2 |
| `mercurius` | npm | All versions | 8.13.2 |
| `mercurius` | npm | From 9.0.0 | 11.5.0 |
| `mercurius` | npm | From 9.0.0 | 11.5.0 |

Products: Mercurius Project Mercurius.

## How do I fix CVE-2023-22477?

Upgrade mercurius to a fixed version for your release line: 8.13.2 or 11.5.0.

## Is CVE-2023-22477 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-22477 exists.

## Other vulnerabilities in mercurius-js mercurius

- [CVE-2021-43801](https://insights.sbomify.com/CVE-2021-43801/): Uncaught Exception in mercurius (high 7.5)
- [CVE-2025-64166](https://insights.sbomify.com/CVE-2025-64166/): Mercurius: Incorrect Content-Type parsing can lead to CSRF attack (medium 5.4)
- [CVE-2026-30241](https://insights.sbomify.com/CVE-2026-30241/): Mercurius: queryDepth limit bypassed for WebSocket subscriptions (low 2.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-22477 and fix it if it is affected.

What it is: CVE-2023-22477 is a medium-severity denial of service vulnerability in mercurius-js mercurius, published on 9 Jan 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-22477 exists.

Affected packages and fixed versions:
- mercurius (npm): affected all versions; fixed in 8.13.2
- mercurius (npm): affected all versions; fixed in 8.13.2
- mercurius (npm): affected from 9.0.0; fixed in 11.5.0
- mercurius (npm): affected from 9.0.0; fixed in 11.5.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-22477/ (Markdown: https://insights.sbomify.com/CVE-2023-22477/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-22477
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-22477
- OSV: https://osv.dev/vulnerability/CVE-2023-22477

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-22477/
Summaries are generated and may contain mistakes; the official description above is the record.