Panelv4

When an originless Agent composes redirect and shared cache interceptors, the system determines whether to store the final response under the original request key by inspecting only the final redirect hop. This allows a redirect that passes through an untrusted origin and returns to a trusted origin to be cached under the trusted key. Consequently, the `Vary` header of an intermediate hop may be dropped, potentially serving responses that vary on `Authorization` or `Cookie` to different users. Additionally, the `no-cache` or `default-uncacheable` status of an intermediate hop may be ignored, allowing a non-storable redirect to be treated as a cacheable entry. An attacker controlling a redirect target from a trusted URL could poison the cached entry or cause a private, per-user response to be served to subsequent callers.

When an application utilizes parameterized prefix and `rewritePrefix` options to pin clients to a fixed upstream path, the plugin substitutes URL-decoded route parameters into `rewritePrefix` without re-encoding them. An unauthenticated remote attacker can provide a parameter value encoding a path separator with a fragment or query delimiter. This decodes into actual separators and delimiters that inject additional upstream path segments and remove the mandatory suffix the `rewritePrefix` was intended to enforce. This allows the attacker to reach upstream locations outside the intended prefix, resulting in path-restriction bypass, which may lead to server-side request forgery (SSRF) or authorization bypass in the proxied service.

This plugin forwards requests to an upstream HTTP server. It fails to properly validate proxy paths because it only checks for forward-slash dot-segments. The WHATWG URL parser normalizes backslashes and their percent-encoded forms into forward slashes for http, https, ws, and wss schemes. Consequently, a path using backslash dot-segments can bypass traversal checks, allowing unauthenticated requests to escape intended prefixes and access unintended upstream endpoints. This results in a confidentiality impact and limited integrity impact.