Summary
Nuxt: Route rules are matched against the raw request path, so a percent-encoded segment can bypass appMiddleware on dynamic and catch-all routes
Nuxt compared routeRules keys against the raw request path, without decoding percent-encoding, while the router decodes parameters when it resolves a route. A request whose path is percent-encoded can therefore resolve to a page while failing to match the route rule meant to protect it, so the rule's appMiddleware never runs, including during server rendering.
Workarounds
If you cannot upgrade, do not rely on a routeRules key alone to protect a route. Attach the middleware to the page itself, which binds it to the resolved route rather than to the raw path string:
<script setup lang="ts">
definePageMeta({ middleware: 'auth' })
</script>
Credits
Thanks to @sushi-gif, whose report that route rules keyed with non-ASCII paths never match the routes generated for those pages prompted the review that found this issue.
Impact
For a page served through a dynamic or catch-all route, an attacker can percent-encode a character in the path to skip the rule:
export default defineNuxtConfig({
routeRules: {
'/users/admin': { appMiddleware: 'auth' },
},
})
Requesting /users/%61dmin still renders app/pages/users/[id].vue with id decoded to admin, but the rule keyed /users/admin does not match, so auth does not run and the server renders and returns the gated page to an unauthenticated visitor. No privileges and no user interaction are required, and only ASCII characters are involved.
Purely static ASCII routes are not affected: static segments are matched without decoding, so a request for /%61dmin does not resolve to the page registered at /admin and 404s instead of rendering.
The rule keys affected are the ones carried in the app manifest and consumed by the app: appMiddleware, redirect, appLayout, ssr, prerender, and the payload flags derived from cache, isr and swr.
If you have pinned or overridden dependency versions below what your Nuxt release declares, a release outside the affected ranges can still be exposed, so do not conclude from a single reproduction that you are unaffected.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-114131 has a CVSS score of 6.5 (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 (4.4.4, 3.21.4); 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
Releases from 4.4.4 and 3.21.4 are not affected, because their dependency floor requires a version of the underlying HTTP layer that normalises percent-encoding in the request path before routing, which removes the mismatch in a default install.
The comparison itself is fixed in [email protected] and [email protected]: route-rule keys and lookup paths are now decoded (and, unless router.options.sensitive is set, case-folded) before they are compared. Reserved escapes such as %2F are left encoded, so decoding cannot introduce extra path segments, and paths that cannot be decoded are matched verbatim. Upgrading to those releases is recommended, since it fixes the comparison rather than relying on a dependency to normalise the input, and it also restores route rules for pages whose paths contain non-ASCII characters.
Frequently Asked Questions
- What is CVE-2026-114131? CVE-2026-114131 is a medium-severity incorrect authorization vulnerability in nuxt (npm), affecting versions >= 4.0.0, < 4.4.4. It is fixed in 4.4.4, 3.21.4. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-114131? CVE-2026-114131 has a CVSS score of 6.5 (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 are affected by CVE-2026-114131? nuxt (npm) versions >= 4.0.0, < 4.4.4 is affected.
- Is there a fix for CVE-2026-114131? Yes. CVE-2026-114131 is fixed in 4.4.4, 3.21.4. Upgrade to this version or later.
- Is CVE-2026-114131 exploitable, and should I be worried? Whether CVE-2026-114131 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-2026-114131 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-2026-114131?
- Upgrade
nuxtto 4.4.4 or later - Upgrade
nuxtto 3.21.4 or later
- Upgrade