# 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.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **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:** Yes
- **Published:** 22 May 2026
- **Updated:** 26 May 2026
- **Also known as:** DEBIAN-CVE-2026-40295, GHSA-jp94-3292-c3xv, UBUNTU-CVE-2026-40295

## 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 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-40295?

2 open source packages ship an affected version, including devise. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `devise` | RubyGems | All versions | 5.0.4 |
| `devise` | RubyGems | All versions | 5.0.4 |

Products: 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

- [CVE-2015-8314](https://insights.sbomify.com/CVE-2015-8314/): Devise Gem for Ruby Unauthorized Access Using "Remember Me" Cookie (high 7.5)
- [CVE-2026-32700](https://insights.sbomify.com/CVE-2026-32700/): Devise has a confirmable "change email" race condition that permits user to confirm email they have no access to (medium 6.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40295 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-40295 in the wild and no public exploit code.

Affected packages and fixed versions:
- devise (RubyGems): affected all versions; fixed in 5.0.4
- devise (RubyGems): affected all versions; fixed in 5.0.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40295/ (Markdown: https://insights.sbomify.com/CVE-2026-40295/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40295
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40295
- OSV: https://osv.dev/vulnerability/CVE-2026-40295

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40295/
Summaries are generated and may contain mistakes; the official description above is the record.