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.
- 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
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
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 | 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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-126343 being exploited?
There is no known exploitation of CVE-2026-126343 in the wild and no public exploit code.
Sources
Also known as GHSA-qv5m-9pm6-hqp3.