CVE-2025-61686
CriticalCVSS 9.1Exploitation Probability (EPSS)
Very high risk97th percentile - higher than 97% of all known CVEs
Summary
In React Router and Remix Run libraries, a vulnerability allows reading/writing session files outside the specified directory when using createFileSessionStorage() with an unsigned cookie. An attacker can cause the session to access locations outside the intended session file directory, depending on web server process permissions.
Risk Assessment
The risk involves potential unauthorized access to session files outside the intended directory, which could lead to session data leakage or manipulation if the application returns session information in responses.
Recommendation
Immediately update libraries: @react-router/node to version 7.9.4, @remix-run/deno to version 2.17.2, and @remix-run/node to version 2.17.2. Additionally, use signed cookies for file-based sessions.
Original NVD description (English source)
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.