GHSA-9phm-9p8f-hw5m is a medium-severity (CVSS 6.1) Open Redirect vulnerability in nitro. A fix is available for nitro — see the affected versions and patch details below.
Nitro has an Open Redirect via Protocol-Relative URL Bypass in Wildcard Route Rules
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-9phm-9p8f-hw5m.
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.
How urgent is this, really
GHSA-9phm-9p8f-hw5m plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
nitronpmnitropacknpmDescription
A redirect route rule like:
routeRules: {
"/legacy/**": { redirect: "/**" }
}
is intended to rewrite paths within the same host. Before the patch, an attacker could turn the rewrite into a cross-host redirect by sliding an extra slash in after the rule prefix. Example exploit:
GET /legacy//evil.com
Nitro stripped /legacy from the matched pathname and joined the remainder against the rule's target. The remainder was //evil.com, which the join preserved verbatim, so Nitro responded with Location: //evil.com. Browsers resolve //evil.com as a protocol-relative URL against the current scheme, sending the user to https://evil.com.
Are you affected?
Users may be affected if all of the following are true:
- Their project uses Nitro's
routeRuleswith aredirectentry. - The target uses a
/**wildcard suffix to forward sub-paths (e.g.redirect: "/**",redirect: "/new/**",proxy: { to: "http://upstream/**" }). - The
redirectrule is not handled natively at the CDN layer. Thevercel,netlify,cloudflare-pages, andedgeonepresets translaterouteRules.redirectinto platform config (vercel.json,_redirects, EdgeOne v3 config) and serve the redirect at the edge — those deployments bypass the Nitro runtime entirely and are not affected. Every other preset executes the redirect through the Nitro runtime and can be vulnerable.
Impact
Open redirect from any host serving Nitro with a wildcard redirect rule. The redirect target is fully attacker-controlled, the URL looks legitimate (it starts with the victim's domain), and the browser silently follows it.
Patched versions
Upgrade to one of:
- 2.13.4 or later (or upgrade lockfile with latest ufo 1.6.4+)
- 3.0.260429-beta or later (https://github.com/nitrojs/nitro/pull/4236)
The fix has two parts:
ufois bumped to^1.6.4(unjs/ufo@5cd9e67), which collapses any run of leading slashes to a single/insidewithoutBase. This covers the typical"/scope/**"rule.- The Nitro runtime additionally collapses leading
//before joining when the rule path itself is/**(in rare case which casewithoutBaseis never called and the raw pathname flows straight intojoinURL("", …)).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nitro | all versions | 3.0.260429-betanpm install nitro@3.0.260429-beta |
| 📦npm | nitropack | all versions | 2.13.4npm install nitropack@2.13.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nitro, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nitro to 3.0.260429-beta or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9phm-9p8f-hw5m 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-9phm-9p8f-hw5m can be triaged on real exposure rather than presence alone.
Tailored to GHSA-9phm-9p8f-hw5m. 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-9phm-9p8f-hw5m in your dependencies?
O3 Security finds GHSA-9phm-9p8f-hw5m across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.