Nuxt dev server exposes private runtime config through the Nitro dev bundleGHSA-648h-gw55-m2g7
MEDIUMFix: nuxt/nuxt@12b58f9GHSA-648h-gw55-m2g7 is a medium-severity (CVSS 5.9) Information Exposure vulnerability in @nuxt/vite-builder. A fix is available for @nuxt/vite-builder — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- 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-648h-gw55-m2g7.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-648h-gw55-m2g7 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 398,142 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
@nuxt/vite-buildernpmDescription
Summary
With Nitro 2 (the default server engine in Nuxt 3 and Nuxt 4), the Nitro development server bundle written by nuxt dev can be fetched through the Vite dev server. Nitro inlines the resolved runtimeConfig into that bundle, so private runtime config values that were resolved at build time can be read by anyone with HTTP access to the dev server.
Impact
nuxt dev writes the Nitro development server bundle to <buildDir>/dev/index.mjs (by default .nuxt/dev/index.mjs). The build directory is inside the directories Nuxt passes to Vite's server.fs.allow, so the bundle is served by the dev server:
curl http://<dev-server>/_nuxt/@fs/<absolute-path-to-project>/.nuxt/dev/index.mjs
The response contains every private (non-public) runtime config value that was resolved at build time. That includes values set in nuxt.config, such as a secret read from .env:
export default defineNuxtConfig({
runtimeConfig: {
apiSecret: process.env.API_SECRET,
},
})
From Nuxt 4.6.0, it also includes the generated development appSecret. Vite's default deny list blocks .env itself, but not the bundle containing values read from it.
Exploitation requires direct HTTP access to the dev server. nuxt dev listens on localhost by default, so this mainly affects dev servers that are exposed to a network (for example with --host, a published container port or a tunnel). As far as we can tell, a malicious website cannot read the file through a developer's browser: Vite's CORS and host checks prevent pages on other origins from reading the response.
Production builds are not affected, because the Vite dev server is not used and the server bundle is not served. Nuxt projects using Nitro 3 do not write the server bundle to disk in development and are not affected. Private runtime config values that are left empty in nuxt.config and supplied through NUXT_* environment variables are applied when the server starts, are not inlined into the bundle, and are not exposed.
Patches
Fixed in @nuxt/vite-builder 4.6.3, which nuxt 4.6.3 depends on. The dev server now adds Nitro's development output directory to Vite's server.fs.deny, keeping Vite's default deny list.
Nuxt 3 has reached end of life and will not receive a fix.
Workarounds
Avoid exposing the dev server to untrusted networks. Alternatively, set private runtime config keys to an empty default in nuxt.config and provide their values with the matching NUXT_* environment variables (for example runtimeConfig: { apiSecret: '' } with NUXT_API_SECRET in .env).
If a dev server has been reachable by untrusted clients, rotate any credentials that were set through runtimeConfig in nuxt.config.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @nuxt/vite-builder | ≥ 3.0.0&&< 4.6.3 | 4.6.3npm install @nuxt/vite-builder@4.6.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @nuxt/vite-builder, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @nuxt/vite-builder to 4.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-648h-gw55-m2g7 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is GHSA-648h-gw55-m2g7 in your dependencies?
Find it across npm, including transitive dependencies.