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CVE Record

CVE-2025-61686: React Router has Path Traversal in File Session Storage

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.

CriticalCVSS 9.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

React Router and Remix applications can be exposed when they store sessions in files and use an unsigned session cookie. An attacker may influence where the server reads or writes session data outside the intended directory. The issue is serious because it can affect integrity and availability, but file contents are not directly returned to the attacker.

Executive priority

Prioritize remediation for internet-facing React Router or Remix services using file-based sessions. Treat this as urgent where session state controls authorization, account state, or operational workflows.

Technical view

CVE-2025-61686 is a CWE-22 path traversal in createFileSessionStorage() affecting @react-router/node 7.0.0 through 7.9.3 and @remix-run/node or @remix-run/deno before 2.17.2. It requires file session storage with an unsigned cookie. Reads only populate session state if the target file matches the expected session format.

Likely exposure

Exposure is likely limited to React Router or Remix deployments using createFileSessionStorage() with unsigned cookies. Risk depends on server process file permissions and application logic that trusts or returns session data.

Exploitation context

The source bundle reports network-reachable, unauthenticated exploitation characteristics in CVSS, but KEV is false and no provided source confirms active exploitation. Successful impact depends on writable or readable paths available to the web server process.

Researcher notes

Do not assume arbitrary file disclosure. Sources state read files are not directly returned and reads require expected session file format. Focus validation on affected versions, unsigned cookie configuration, file permissions, and application behavior using populated session values.

Mitigation direction

  • Upgrade @react-router/node to version 7.9.4 or later.
  • Upgrade @remix-run/node to version 2.17.2 or later.
  • Upgrade @remix-run/deno to version 2.17.2 or later.
  • Review whether createFileSessionStorage() uses unsigned cookies.
  • Check vendor guidance for configuration-specific hardening.

Validation and detection

  • Inventory React Router and Remix package versions in deployed applications.
  • Search application code for createFileSessionStorage() usage.
  • Confirm session cookies are not unsigned in affected deployments.
  • Review web server file permissions around session storage paths.
  • Test that patched versions are deployed in production artifacts.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-22: File access and web shell behavior lookup

File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2025-61686 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.1 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.1CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H3.95.2GitHub_M
9.1CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

9.1Critical
CVSS 3.1 vector shape for CVE-2025-61686Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPreact-router: React Router has Path Traversal in File Session Storage
other:Red Hat severity ratingcvssV3_1
  • 2026-01-10T04:01:55.424Z: Reported to Red Hat.
  • 2026-01-10T02:41:22.741Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
remix-runreact-router@react-router/node >= 7.0.0, < 7.9.4, @remix-run/deno < 2.17.2, @remix-run/node < 2.17.2Listed
Weakness

CWE details

CWE-22

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-22 · source CWE mapping

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs