Miniflux has an Open Redirect via protocol-relative redirect_url in miniflux.app

Open Source Vulnerabilities GO-2025-4226

Miniflux has an Open Redirect via protocol-relative redirect_url in miniflux.app

Open Source Vulnerabilities GHSA-wqv2-4wpg-8hc9

### Summary `redirect_url` is treated as safe when `url.Parse(...).IsAbs()` is false. Protocol-relative URLs like `//ikotaslabs.com` have an empty scheme and pass that check, allowing post-login redirects to attacker-controlled sites. ### Details - `url.Parse("//ikotaslabs.com")` => empty Scheme, Host="ikotaslabs.com". - `IsAbs()` returns false for `//ikotaslabs.com`, so the code treats it as allowed. - Browser resolves `//ikotaslabs.com` to current-origin scheme (e.g. `https://ikotaslabs.com`), enabling phishing flows after login. ### PoC 1. Send or visit: `http://localhost/login?redirect_url=//ikotaslabs.com` 2. Complete normal login flow. 3. After login the app redirects to `https://ikotaslabs.com` (or `http://` depending on origin). ### Acknowledgements This vulnerability was discovered using the automated vulnerability analysis tools **VulScribe** and **PwnML**. The research and tool development were conducted with support from the **MITOU Advanced Program (未踏アドバンスト事業)**, implemented by the **Information-technology Promotion Agency (IPA), Japan**.

Open Source Vulnerabilities CVE-2025-67713

Miniflux 2 is an open source feed reader. Versions 2.2.14 and below treat redirect_url as safe when url.Parse(...).IsAbs() is false, enabling phishing flows after login. Protocol-relative URLs like //ikotaslabs.com have an empty scheme and pass that check, allowing post-login redirects to attacker-controlled sites. This issue is fixed in version 2.2.15.