GHSA-3fw8-66wf-pr7m
Fix: senchalabs/connect@126187cGHSA-3fw8-66wf-pr7m is a Cross-site Scripting (XSS) vulnerability in connect. O3 Security confirms whether GHSA-3fw8-66wf-pr7m is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
methodOverride Middleware Reflected Cross-Site Scripting in connect
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.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
connectnpmDescription
Connect is a stack of middleware that is executed in order in each request.
The "methodOverride" middleware allows the http post to override the method of the request with the value of the "_method" post key or with the header "x-http-method-override".
Because the user post input was not checked, req.method could contain any kind of value. Because the req.method did not match any common method VERB, connect answered with a 404 page containing the "Cannot [method] [url]" content. The method was not properly encoded for output in the browser.
###Example:
~ curl "localhost:3000" -d "_method=<script src=http://nodesecurity.io/xss.js></script>"
Cannot <SCRIPT SRC=HTTP://NODESECURITY.IO/XSS.JS></SCRIPT> /
Recommendation
Update to the newest version of Connect or disable methodOverride. It is not possible to avoid the vulnerability if you have enabled this middleware in the top of your stack.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | connect | all versions | 2.8.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for connect. 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 connect to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3fw8-66wf-pr7m 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-3fw8-66wf-pr7m 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-3fw8-66wf-pr7m. 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-3fw8-66wf-pr7m in your dependencies?
O3 detects GHSA-3fw8-66wf-pr7m across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.