CVE-2025-61686
CRITICAL
GHSA-9583-h5hc-x8cw
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Lifecycle Timeline
3Description
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.
Analysis
React Router (@react-router/node 7.0.0-7.9.3) has a path traversal in file-based session storage when using unsigned cookies. Attackers can manipulate session file paths to read or write arbitrary files on the server.
Technical Context
When createFileSessionStorage() is used with unsigned cookies, the session ID from the cookie is used to construct the file path without sanitization (CWE-22). An attacker can set a session cookie with path traversal sequences to read or overwrite arbitrary files.
Affected Products
@react-router/node 7.0.0-7.9.3, @remix-run/node and @remix-run/deno before 2.17.2
Remediation
Update React Router or Remix. Sign session cookies to prevent tampering.
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External POC / Exploit Code
Leaving vuln.today