CVE-2025-61686 React Router has Path Traversal in File Session Storage
Attackers can read or write files outside the session directory via path traversal in file session storage when using unsigned cookies.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-61686?
CVE-2025-61686 is a critical path traversal vulnerability in remix-run react-router, published on 10 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
React Router is a router for React. In @react-router/node versions 7.0.0 through 7.9.3, @remix-run/deno prior to version 2.17.2, and @remix-run/node prior to version 2.17.2, if createFileSessionStorage() is being used from @react-router/node (or @remix-run/node/@remix-run/deno in Remix v2) with an unsigned cookie, it is possible for an attacker to cause the session to try to read/write from a location outside the specified session file directory. The success of the attack would depend on the permissions of the web server process to access those files. Read files cannot be returned directly to the attacker. Session file reads would only succeed if the file matched the expected session file format. If the file matched the session file format, the data would be populated into the server side session but not directly returned to the attacker unless the application logic returned specific session information. This issue has been patched in @react-router/node version 7.9.4, @remix-run/deno version 2.17.2, and @remix-run/node version 2.17.2.
Weakness: CWE-22
Which versions are affected by CVE-2025-61686?
6 open source packages ship an affected version, including @react-router/node, @remix-run/deno and @remix-run/node. It affects 3 products.
| Package | Affected | Fixed in |
|---|---|---|
@react-router/node npm | From 7.0.0 | 7.9.4 |
@react-router/node npm | From 7.0.0 | 7.9.4 |
@remix-run/deno npm | All versions | 2.17.2 |
@remix-run/deno npm | All versions | 2.17.2 |
@remix-run/node npm | All versions | 2.17.2 |
@remix-run/node npm | All versions | 2.17.2 |
Products include Shopify React-Router\/Node, Shopify Remix-Run\/Deno, Shopify Remix-Run\/Node.
How do I fix CVE-2025-61686?
Upgrade @react-router/node to 7.9.4 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2025-61686 being exploited?
There is no known exploitation of CVE-2025-61686 in the wild and no public exploit code.
Public exploit code: 3 proofs of concept on GitHub.
Sources
Also known as GHSA-9583-h5hc-x8cw.