GHSA-r557-wffq-wvrc: @astrojs/node: Backslash-prefixed paths not recognized as internal by trailing-slash redirect

Impact With trailingSlash: 'always' configured, the @astrojs/node standalone server's static file handler appends a trailing slash to request paths and issues a 301 redirect. Paths beginning with /\ (slash-backslash) were not recognized as internal paths, so the handler would echo the raw path back in the Location header. Because browsers treat \ as / per the WHATWG URL specification, the resulting redirect could resolve to an external host. Preconditions: - trailingSlash: 'always' must be set (non-default; the default is 'ignore') - The request path must not have a file extension in its final segment - An attacker must deliver the crafted link to a user Patches Fixed by treating backslash-prefixed paths the same as //-prefixed paths in isInternalPath(), so they are no longer rewritten with a trailing slash. Workarounds Use the default trailingSlash: 'ignore' setting, which does not issue trailing-slash redirects in the static file handler. References - WHATWG URL spec: backslash normalization