Qwik is a performance focused javascript framework. Prior to version 1.19.0, an Open Redirect vulnerability in Qwik City's default request handler middleware allows a remote attacker to redirect users to arbitrary protocol-relative URLs. Successful exploitation permits attackers to craft convincing phishing links that appear to originate from the trusted domain but redirect the victim to an attacker-controlled site. This issue has been patched in version 1.19.0.

Affected: npm: @builder.io/qwik-city

### Summary

**Description** An Open Redirect (CWE-601) vulnerability in Qwik City's default request handler middleware allows a remote attacker to redirect users to arbitrary protocol-relative URLs. Successful exploitation permits attackers to craft convincing phishing links that appear to originate from the trusted domain but redirect the victim to an attacker-controlled site. This affects qwik-city before version 1.19.0. This has been patched in qwik-city version 1.19.0.

### Impact Qwik City automatically applies the `fixTrailingSlash` middleware to page routes to ensure URL consistency. This vulnerability impacts all Qwik City applications deployed to runtimes that have a catch-all path to match arbitrary domains and that do not automatically normalize URL paths (e.g. Bun).

Exploitation allows an attacker to craft links that trigger a 301 redirect to arbitrary protocol-relative URLs. Browsers interpret this Location header as a protocol-relative URL, redirecting the user to attacker-controlled domains. This can enable phishing attacks and token theft among other common open redirect exploits.

### Patches This has been patched in qwik-city version 1.19.0. Users are strongly encouraged to update to the latest available release.