React Router has Path Traversal in File Session Storage

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS

• CVE-2025-61686: 17.35% estimated exploitation activity in the next 30 days; percentile 97.12 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

8 Jan 2026, 20:45 UTC

Last modified by the source

18 Sep 2026, 21:15 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9583-h5hc-x8cw

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-9583-h5hc-x8cw

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-9583-h5hc-x8cw

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# Patch Next advisory brief: CVE-2025-61686

Advisory: React Router has Path Traversal in File Session Storage
IDs: CVE-2025-61686, GHSA-9583-h5hc-x8cw
Record: https://patchnext.com/advisories/cve-2025-61686 (revision 3, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @react-router/node 7.9.4; @remix-run/deno 2.17.2; @remix-run/node 2.17.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @react-router/node: affected >= 7.0.0, <= 7.9.3; fixed in 7.9.4
- npm @remix-run/deno: affected <= 2.17.1; fixed in 2.17.2
- npm @remix-run/node: affected <= 2.17.1; fixed in 2.17.2

## Suggested inspection (read-only)
- `npm ls @react-router/node --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @remix-run/deno --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @remix-run/node --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @react-router/node, @remix-run/deno, @remix-run/node.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9583-h5hc-x8cw (GitHub-reviewed advisory GHSA-9583-h5hc-x8cw lists affected ranges: npm @react-router/node >=7.0.0 =0 =0 <=2.17.1)
- Verified: https://osv.dev/vulnerability/GHSA-9583-h5hc-x8cw (OSV record GHSA-9583-h5hc-x8cw lists affected ranges: npm @react-router/node >=7.0.0 =0 =0 <2.17.2 (fixed))

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