Description

Nuxt: Unauthenticated out-of-memory crash via unbounded v-for expansion in island rendering

Impact

An unauthenticated attacker can crash a Nuxt server that renders any island / server component containing a v-for over a prop (for example v-for="n in count" or a <slot v-for>). Because the island URL hash is a non-secret digest of the request, the attacker can compute a valid hash for arbitrary props and send the iterated prop as a large integer. The server then expands the v-for to that many nodes during SSR, allocating memory proportional to the attacker's number. Reporter figures: count=8000000 produced a 142.9 MB response; count=40000000 (and items=4000000 on a slot list) produced an out-of-memory crash of the worker from a single ~130-byte request. Both the plain v-for path (Vue's ssrRenderList) and the slot path (vforToArray) are affected.

Patches

Fixed in [email protected] and [email protected]. Island/server-component v-for sources are now clamped to a maximum iteration count (MAX_VFOR_LENGTH = 100000) at the render boundary, covering the plain path, the <slot v-for> element, and the vforToArray slot-props helper. Combined with the body-size cap (GHSA-9pgf-384g-p7mv), a single island render can no longer allocate without bound regardless of which v-for path is used or whether the prop arrives as an integer or an array.

Workarounds

Avoid v-for directly over an unclamped prop in server components, or clamp the count in the component (v-for="n in Math.min(count, 1000)"). A body-size limit in front of /__nuxt_island/ only mitigates array-shaped inputs, not the integer-amplification case.

References

Bound helper: packages/nuxt/src/app/components/vfor.ts

Transform: packages/nuxt/src/components/plugins/islands-transform.ts

Slot helper: packages/nuxt/src/app/components/utils.ts (vforToArray)

Mitigation

Aliases

References