Nuxt prior 3.21.10/4.5.1 Internal Island Renderer Endpoint /__nuxt_island/_.json resource consumption

Summaryinfo

A vulnerability categorized as problematic has been discovered in Nuxt. The affected element is an unknown function of the file /__nuxt_island/_.json of the component Internal Island Renderer Endpoint. The manipulation results in resource consumption. This vulnerability is identified as CVE-2026-71321. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Nuxt. Affected is an unknown functionality of the file /__nuxt_island/_.json of the component Internal Island Renderer Endpoint. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. CVE summarizes:

Nuxt is an open-source web development framework for Vue.js. From 3.1.0 until 3.21.10 and 4.5.1, the internal island renderer endpoint `/__nuxt_island/...` decodes and hashes attacker-controlled JSON body input with destr and ohash before validating the URL-resident hash. An unauthenticated `POST /__nuxt_island/_.json` with a large JSON body is fully read, parsed, hashed, and then rejected, which wastes CPU on Nitro single event loop and delays concurrent requests. No valid hash and no authentication are required. This issue is fixed in 3.21.10 and 4.5.1.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-71321 since 08/05/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

By approaching the search of inurl:__nuxt_island/_.json it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 3.21.10 or 4.5.1 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

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• Nuxt

Website

• Product: https://github.com/nuxt/nuxt/

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Once again VulDB remains the best source for vulnerability data.

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