undici vulnerable to cross-user information disclosure via cross-origin redirect revalidation

undici is an HTTP client for Node.js. In versions 7.0.0 through 7.30.1 and 8.0.0 through 8.12.3, when an Agent composes the redirect and shared cache interceptors, a cached response that is revalidated with a conditional request can be validated by a 304 Not Modified from a different origin. When the origin that stored the response redirects the conditional revalidation request to another origin, the redirect handler strips origin-bound credential headers but not the cache-generated If-None-Match or If-Modified-Since validators, so the redirect destination receives the original origin's validator and undici treats its 304 as successful revalidation of the stored representation. As a result, a shared cache can serve the original origin's stored authenticated response, including one gated by Authorization, to a later unauthenticated caller. The issue is fixed in undici 7.30.2 and 8.12.4, and users should upgrade to one of those versions or later. As a workaround, compose the interceptors as cache then redirect, use per-origin dispatchers and cache stores, or disable shared caching on redirect-capable requests.