Nuxt: `__nuxt_island` endpoint does not bind responses to request props, enabling shared-cache poisoning
Date: 2026-05
Affected: npm/@nuxt/nitro-server, npm/@nuxt/nitro-server, npm/nuxt
Attack vector: xss
Category: vulnerability-disclosure
Severity: Low
CVE: CVE-2026-46342
CWE: CWE-349
CWE-444
CWE-79

### Summary The `/__nuxt_island/*` endpoint accepts attacker-controlled `props` query/body parameters and renders any island component without verifying that the URL-resident hash (`<Name>_<hashId>.json`) was actually issued for those inputs by `<NuxtIsland>`. The hash is computed and embedded client-side but never validated server-side, so the same path can return materially different responses depending on the query. Island components are documented as rendering independently of route context - page middleware does not apply to them, and they are intentionally cacheable as a function of their props. This advisory does **not** treat that contract as a vulnerability. It treats the absence of a binding between the URL the cache keys on and the response served at that URL as one. ### Impact In applications where a CDN or reverse-proxy in front of the app caches `/__nuxt_island/*` keyed by path only (ignoring query) - a documented misconfiguration class, see GHSA-jvhm-gjrh-3h93 - an attacker can prime the cache for a path with their own choice of props, and subsequent users requesting the same path receive the attacker's rendered HTML rather than the response intended for them. The cache entry persists until normal expiry. Where the affected island has any prop flowing into an unsafe HTML sink in application code (`v-html`, `innerHTML`, a third-party renderer treating a prop as HTML), this becomes stored XSS in the embedding page's origin until the cache entry expires. `Htt


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Architectural layers (MAESTRO):