CVE-2026-40255: 
JavaScript vulnerability analysis and mitigation

Impact

The response.redirect().back() method in @adonisjs/http-server is vulnerable to open redirects. The method reads the Referer header from the incoming HTTP request and redirects to that URL without validating the host. An attacker who can influence the Referer header (for example, by linking a user through an attacker-controlled page before a form submission) can cause the application to redirect users to a malicious external site. This affects all AdonisJS applications that use response.redirect().back() or response.redirect('back'). The vulnerability is classified as CWE-601: URL Redirection to Untrusted Site ('Open Redirect').

Patches

This has been fixed in @adonisjs/http-server version 8.2.0. The back() method now validates the Referer header's host against the request's own Host header. Referrers from unrecognized hosts are rejected and the redirect falls back to / (or a developer-provided fallback URL). Applications that operate across multiple domains can configure additional trusted hosts via the redirect.allowedHosts option in config/app.ts. Users should upgrade to @adonisjs/http-server@^8.2.0 (or @adonisjs/core@^7.4.0 if using the core meta-package).

Workarounds

If upgrading is not immediately possible, avoid using response.redirect().back() in routes that are reachable by unauthenticated users or from pages that accept external traffic. Instead, redirect to a known safe path explicitly using response.redirect().toPath('/dashboard').

References

• CWE-601: URL Redirection to Untrusted Site
• OWASP: Unvalidated Redirects and Forwards