CVE-2026-40295 Devise: Open Redirect via Unvalidated `request.referrer` in Timeoutable Session Timeout Handler
Attackers can redirect users with expired sessions to malicious sites via unvalidated referrer headers in Devise's timeout handler, enabling phishing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-40295?
CVE-2026-40295 is a medium-severity vulnerability in heartcombo devise, published on 22 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Devise is an authentication solution for Rails based on Warden. In versions 5.0.3 and below, when the Timeoutable module is enabled in Devise, the FailureApp#redirect_url method returns request.referrer — the HTTP Referer header, which is attacker-controllable — without validation for any non-GET request that results in a session timeout. An attacker who hosts a page with an auto-submitting cross-origin form can cause a victim with an expired Devise session to be redirected to an arbitrary external URL. This contrasts with the GET timeout path (which uses server-side attempted_path) and Devise's own store_location_for mechanism (which strips external hosts via extract_path_from_location), both of which are protected; only the non-GET timeout redirect path is unprotected. Expired-session users can be silently redirected from the trusted app domain to attacker-controlled URLs, enabling phishing and malware delivery while bypassing browser warnings. Note: Rails' built-in open-redirect protection does not mitigate this issue. Devise::FailureApp is an ActionController::Metal app with its own isolated copy of the relevant redirect configuration, so config.action_controller.action_on_open_redirect = :raise (and the older raise_on_open_redirects setting) do not reach it. This issue has been fixed in version 5.0.4.
Weakness: CWE-601
Which versions are affected by CVE-2026-40295?
2 open source packages ship an affected version, including devise. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
devise RubyGems | All versions | 5.0.4 |
devise RubyGems | All versions | 5.0.4 |
Products include Heartcombo Devise.
How do I fix CVE-2026-40295?
Upgrade devise to 5.0.4 or later.
Is CVE-2026-40295 being exploited?
There is no known exploitation of CVE-2026-40295 in the wild and no public exploit code.
Other vulnerabilities in heartcombo devise
Sources
Also known as DEBIAN-CVE-2026-40295, GHSA-jp94-3292-c3xv, UBUNTU-CVE-2026-40295.