# CVE-2026-126343: @hono/node-server: Unhandled `ECONNRESET` on the socket during an asynchronous WebSocket upgrade crashes the process

> Unauthenticated clients resetting a WebSocket connection during async upgrade work can crash Hono Node.js apps with WebSocket support enabled.

- **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
- **Harmful if only installed:** No
- **Needs a specific call:** Yes
- **Fix available:** Yes
- **Published:** 12 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-qv5m-9pm6-hqp3

## What is CVE-2026-126343?

CVE-2026-126343 is a medium-severity denial of service vulnerability in honojs node-server, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

@hono/node-server allows running the Hono application on Node.js. From 2.0.0 until 2.1.6, the WebSocket upgrade handler waits for the Hono application to finish asynchronous middleware or handler work without first attaching an error listener to the socket. If an unauthenticated client resets the TCP connection during that window, the socket emits an unhandled ECONNRESET error and terminates the Node.js process. If a global uncaughtException handler suppresses termination, the pending upgrade waiter is not released and repeated requests can grow the heap. This affects applications that enable WebSocket support and perform asynchronous work on the upgrade path. This issue is fixed in version 2.1.6.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-126343?

1 open source package ship an affected version, including @hono/node-server.

An affected version is only exploitable if your software uses the vulnerable function or option. Many projects that include it are not exposed.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@hono/node-server` | npm | From 2.0.0 | 2.1.6 |

## How do I fix CVE-2026-126343?

Upgrade @hono/node-server to 2.1.6 or later.

## Is CVE-2026-126343 being exploited?

There is no known exploitation of CVE-2026-126343 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-126343 and fix it if it is affected.

What it is: CVE-2026-126343 is a medium-severity denial of service vulnerability in honojs node-server, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-126343 in the wild and no public exploit code.
Exposure: An affected version is only exploitable if your software uses the vulnerable function or option. Many projects that include it are not exposed.

Affected packages and fixed versions:
- @hono/node-server (npm): affected from 2.0.0; fixed in 2.1.6

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-2026-126343/ (Markdown: https://insights.sbomify.com/CVE-2026-126343/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-126343
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126343
- OSV: https://osv.dev/vulnerability/CVE-2026-126343

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-126343/
Summaries are generated and may contain mistakes; the official description above is the record.