GHSA-m4w9-gch5-c2g4
MEDIUMclient-certificate-auth Vulnerable to Open Redirect via Host Header Injection in HTTP-to-HTTPS redirect
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
client-certificate-authReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Versions 0.2.1 and 0.3.0 of client-certificate-auth contain an open redirect vulnerability. The middleware unconditionally redirects HTTP requests to HTTPS using the unvalidated Host header, allowing an attacker to redirect users to arbitrary domains.
Vulnerable Code
// lib/clientCertificateAuth.js (versions 0.2.1, 0.3.0)
if (!req.secure && req.header('x-forwarded-proto') != 'https') {
return res.redirect('https://' + req.header('host') + req.url);
}
Attack Scenario
- Attacker crafts a link:
http://vulnerable-app.example.com/login - When victim clicks, attacker intercepts and injects header:
Host: attacker.com - Server responds:
302 Found → https://attacker.com/login - Victim is redirected to attacker-controlled site
Impact
- Phishing: Attackers can use trusted domain links to redirect victims to credential-harvesting pages
- OAuth/SSO Token Theft: In authentication flows, authorization codes or tokens may leak via redirect
- Referer Leakage: Sensitive URL parameters may be exposed to attacker domains via the Referer header
- Cache Poisoning: In deployments with shared caches, malicious redirects may be cached and served to other users
Exploitability
Exploitation requires that HTTP traffic reaches the Node.js application without TLS termination setting x-forwarded-proto: https. This condition is uncommon in production deployments behind modern reverse proxies or load balancers, which limits real-world exploitability.
Fix
The vulnerable redirect behavior has been completely removed in version 1.0.0.
npm install client-certificate-auth@^1.0.0
Workarounds
If upgrading is not immediately possible:
- Block HTTP traffic at the network/load balancer level
- Ensure your reverse proxy always sets
x-forwarded-proto: https - Add middleware before
clientCertificateAuthto validate theHostheader against an allowlist
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | client-certificate-auth | ≥ 0.2.1&&< 1.0.0 | 1.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for client-certificate-auth. 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 client-certificate-auth to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m4w9-gch5-c2g4 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-m4w9-gch5-c2g4 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-m4w9-gch5-c2g4. 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-m4w9-gch5-c2g4 in your dependencies?
O3 detects GHSA-m4w9-gch5-c2g4 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.