Summary
Nuxt dev server exposes private runtime config through the Nitro dev bundle
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.
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.
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.
CVE-2026-119199 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.6.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
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.
Frequently Asked Questions
- What is CVE-2026-119199? CVE-2026-119199 is a medium-severity security vulnerability in @nuxt/vite-builder (npm), affecting versions >= 3.0.0, < 4.6.3. It is fixed in 4.6.3.
- How severe is CVE-2026-119199? CVE-2026-119199 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @nuxt/vite-builder are affected by CVE-2026-119199? @nuxt/vite-builder (npm) versions >= 3.0.0, < 4.6.3 is affected.
- Is there a fix for CVE-2026-119199? Yes. CVE-2026-119199 is fixed in 4.6.3. Upgrade to this version or later.
- Is CVE-2026-119199 exploitable, and should I be worried? Whether CVE-2026-119199 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-119199 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-119199? Upgrade
@nuxt/vite-builderto 4.6.3 or later.