Coder vulnerable to post-auth URL redirection to untrusted site ('Open Redirect')

Summary

### Summary An issue on Coder's login page allows attackers to craft a Coder URL that when clicked by a logged in user could redirect them to a website the attacker controls, e.g. https://google.com. ### Details On the login page, Coder checks for the presence of a `redirect` query parameter. On successful login, the user would be redirected to the location of the parameter. Improper sanitization allows attackers to specify a URL outside of the Coder application to redirect users to. ### Impact Coder users could potentially be redirected to a untrusted website if tricked into clicking a URL crafted by the attacker. Coder authentication tokens are **not** leaked to the resulting website. To check if your deployment is vulnerable, visit the following URL for your Coder deployment: - `https://<coder url>/login?redirect=https%3A%2F%2Fcoder.com%2Fdocs` ### Patched Versions This vulnerability is remedied in - v2.16.1 - v2.15.3 - v2.14.4 All versions prior to 2.3.1 are not affected. ### Thanks - https://github.com/jchristov ### References https://github.com/coder/coder/security/advisories/GHSA-wcx9-ccpj-hx3c https://github.com/coder/coder/commit/69c1d981e3131e50d52b01f6a360abadaad699e6