CVE-2025-61686

CRITICAL

React Router <7.9.3 - Path Traversal

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 3 public exploits for CVE-2025-61686. PoCs published by boroeurnprach, FlowerWitch, Kai-One001.

AI-analyzed exploit summary This PoC demonstrates a directory traversal vulnerability in a Node.js application using `@react-router/node`'s `createFileSessionStorage`. The exploit manipulates the session cookie to read arbitrary files (e.g., `/etc/passwd`) via path traversal, confirmed through JSON parsing errors.

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.

Exploits (3)

nomisec WORKING POC
by boroeurnprach · poc
https://github.com/boroeurnprach/CVE-2025-61686-PoC

This PoC demonstrates a directory traversal vulnerability in a Node.js application using `@react-router/node`'s `createFileSessionStorage`. The exploit manipulates the session cookie to read arbitrary files (e.g., `/etc/passwd`) via path traversal, confirmed through JSON parsing errors.

Classification
Working Poc 95%
Attack Type
Info Leak
Complexity
Trivial
Reliability
Reliable
Target: Node.js application using @react-router/node (version unspecified)
No auth needed
Prerequisites: Access to the target server's session cookie endpoint · Server running vulnerable `@react-router/node` version
devstral-2 · analyzed Feb 16, 2026 Full analysis →
nomisec WORKING POC
by FlowerWitch · poc
https://github.com/FlowerWitch/CVE-2025-61686_docker

This repository contains a working proof-of-concept for CVE-2025-61686, demonstrating a directory traversal vulnerability in react-router's fileStorage session handling. The exploit leverages improper path sanitization to write arbitrary files via crafted session cookies.

Classification
Working Poc 95%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: react-router-node versions 7.9.3 and earlier
No auth needed
Prerequisites: Access to the target application's session cookie · Optional: Knowledge of the session secret for signed cookies
devstral-2 · analyzed Feb 16, 2026 Full analysis →
nomisec WORKING POC
by Kai-One001 · poc
https://github.com/Kai-One001/React-Router-CVE-2025-61686-

This repository contains a working proof-of-concept for CVE-2025-61686, a path traversal vulnerability in React Router's file-based session storage. The exploit leverages unsigned cookies to manipulate session IDs, allowing arbitrary file read/write operations on the server.

Classification
Working Poc 95%
Attack Type
Info Leak
Complexity
Moderate
Reliability
Reliable
Target: @react-router/node versions 7.0.0 to 7.9.3
No auth needed
Prerequisites: Server using createFileSessionStorage() · Unsigned cookies (no secrets configured) · Web server process has file system access
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (1)

Core 1
Core References

Scores

CVSS v3 9.1
EPSS 0.0004
EPSS Percentile 13.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-22
Status published
Products (6)
react-router/node 7.0.0 - 7.9.4npm
remix-run/deno 0 - 2.17.2npm
remix-run/node 0 - 2.17.2npm
shopify/react-router\/node 7.0.0 - 7.9.4
shopify/remix-run\/deno < 2.17.2
shopify/remix-run\/node < 2.17.2
Published Jan 10, 2026
Tracked Since Feb 18, 2026