CVE-2025-61686

If applications use createFileSessionStorage() 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.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2025-61686 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (7.9.4, 2.17.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-61686? CVE-2025-61686 is a critical-severity path traversal vulnerability in @react-router/node (npm), affecting versions >= 7.0.0, <= 7.9.3. It is fixed in 7.9.4, 2.17.2. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2025-61686? CVE-2025-61686 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2025-61686?
   • @react-router/node (npm) (versions >= 7.0.0, <= 7.9.3)
   • @remix-run/node (npm) (versions <= 2.17.1)
   • @remix-run/deno (npm) (versions <= 2.17.1)
4. Is there a fix for CVE-2025-61686? Yes. CVE-2025-61686 is fixed in 7.9.4, 2.17.2. Upgrade to this version or later.
5. Is CVE-2025-61686 exploitable, and should I be worried? Whether CVE-2025-61686 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-61686 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-61686?
   • Upgrade @react-router/node to 7.9.4 or later
   • Upgrade @remix-run/node to 2.17.2 or later
   • Upgrade @remix-run/deno to 2.17.2 or later