Impact
When a page is covered by routeRules cache / swr / isr, Nuxt enables runtime payload extraction and serves /<page>/_payload.json. On affected versions the renderer stored the SSR payload in the shared cache:nuxt:payload storage under a path-only key (no cookie, authorization, or cache.varies dimension) and, on a later payload request, returned the cached entry before route middleware / page guards ran again.
As a result, once any authenticated user warms a protected, cached page, a subsequent GET /<page>/_payload.json from an unauthenticated client or a different authenticated user receives the first user's payload: the full SSR data for that route, including anything loaded via useFetch / useAsyncData (for example /api/me: profile, tenant, billing, token-like values). The HTML response stays correctly varied and protected; only the extracted payload leaks. Both cross-user (A warms, B receives A) and unauthenticated disclosure are exploitable. cache.varies does not mitigate it, because the payload cache ignores varies.
Introduced when runtime payload extraction landed for cached routes (#34410); the regression is specific to the 4.x line, where the runtime cache:nuxt:payload storage was added and the import.meta.prerender gate on the payload-cache read/writes was dropped. The 3.x line shipped the same feature with the gate intact and is not affected.
Patches
Fixed in nuxt@4.5.1. Runtime payload-cache reads and writes are again confined to prerendering (import.meta.prerender); at runtime, /<page>/_payload.json follows the normal render path so route middleware, routeRules.appMiddleware, and page guards run for the current request. main / v5 and the 3.x line already had this property, so 3.x is not affected.
Workarounds
- Set
experimental.payloadExtraction: false (reporter-validated): the standalone /_payload.json endpoint returns 404 and the page still serves a 200 with an inline payload.
- Do not apply
cache / swr / isr to authenticated pages that render user-specific SSR data.
- As defense-in-depth, require authentication for
/**/_payload.json at a proxy / CDN.
- After upgrading, purge any CDN / platform cache that may already hold protected payloads.
References
quantumshiro Finder
Impact
When a page is covered by
routeRulescache/swr/isr, Nuxt enables runtime payload extraction and serves/<page>/_payload.json. On affected versions the renderer stored the SSR payload in the sharedcache:nuxt:payloadstorage under a path-only key (no cookie,authorization, orcache.variesdimension) and, on a later payload request, returned the cached entry before route middleware / page guards ran again.As a result, once any authenticated user warms a protected, cached page, a subsequent
GET /<page>/_payload.jsonfrom an unauthenticated client or a different authenticated user receives the first user's payload: the full SSR data for that route, including anything loaded viauseFetch/useAsyncData(for example/api/me: profile, tenant, billing, token-like values). The HTML response stays correctly varied and protected; only the extracted payload leaks. Both cross-user (A warms, B receives A) and unauthenticated disclosure are exploitable.cache.variesdoes not mitigate it, because the payload cache ignoresvaries.Introduced when runtime payload extraction landed for cached routes (#34410); the regression is specific to the 4.x line, where the runtime
cache:nuxt:payloadstorage was added and theimport.meta.prerendergate on the payload-cache read/writes was dropped. The 3.x line shipped the same feature with the gate intact and is not affected.Patches
Fixed in
nuxt@4.5.1. Runtime payload-cache reads and writes are again confined to prerendering (import.meta.prerender); at runtime,/<page>/_payload.jsonfollows the normal render path so route middleware,routeRules.appMiddleware, and page guards run for the current request.main/ v5 and the3.xline already had this property, so 3.x is not affected.Workarounds
experimental.payloadExtraction: false(reporter-validated): the standalone/_payload.jsonendpoint returns 404 and the page still serves a 200 with an inline payload.cache/swr/isrto authenticated pages that render user-specific SSR data./**/_payload.jsonat a proxy / CDN.References