Vulnerability-Lookup

GHSA-337J-9HXR-RHXG

Vulnerability from github – Published: 2026-07-23 19:34 – Updated: 2026-07-23 19:34

Summary

React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration

Details

If application code allows attacker supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for attacker to trigger unexpected constructor execution on the client which would trigger outbound network traffic. This is only possible with very specific (and unlikely) application layer code.

[!NOTE] This does not impact your application if you are using Declarative Mode. This only impacts Framework Mode and Data Mode applications doing manual SSR/hydration

Severity

6.1 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "react-router"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.4.0"
            },
            {
              "fixed": "7.18.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-53666"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-470"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-23T19:34:14Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "If application code allows attacker supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for attacker to trigger unexpected constructor execution on the client which would trigger outbound network traffic.  This is only possible with very specific (and unlikely) application layer code.\n\n\u003e [!NOTE]\n\u003e This does not impact your application if you are using Declarative Mode.  This only impacts Framework Mode and Data Mode applications doing manual SSR/hydration",
  "id": "GHSA-337j-9hxr-rhxg",
  "modified": "2026-07-23T19:34:14Z",
  "published": "2026-07-23T19:34:14Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/pull/15175"
    },
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/remix-run/react-router"
    },
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180"
    },
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/releases/tag/react-router@7.18.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration"
}

CVE-2026-53666 (GCVE-0-2026-53666)

Vulnerability from cvelistv5 – Published: 2026-07-27 21:14 – Updated: 2026-07-28 15:19

Title

React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration

Summary

React Router is a router for React. In versions 6.4.0 through 7.17.0, if application code was written in a way that allows attacker-supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for an attacker to trigger unexpected constructor execution on the client, which would in turn trigger an outbound network request. This is only possible with very specific (and unlikely) application-layer code. Note that this does not impact an application if it is using Declarative Mode. It only impacts Framework Mode and Data Mode applications that perform manual SSR/hydration. This issue has been fixed in version 7.18.0.

Severity

6.1 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-470 - Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')

Assigner

GitHub_M

References

5 references

URL	Tags
https://github.com/remix-run/react-router/securit…	x_refsource_CONFIRM
https://github.com/remix-run/react-router/pull/15175	x_refsource_MISC
https://github.com/remix-run/react-router/commit/…	x_refsource_MISC
https://github.com/remix-run/react-router/blob/ma…	x_refsource_MISC
https://github.com/remix-run/react-router/release…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
remix-run	react-router	Affected: >= 6.4.0, < 7.18.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-53666",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-28T15:09:52.899776Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-28T15:19:58.603Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "react-router",
          "vendor": "remix-run",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 6.4.0, \u003c 7.18.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "React Router is a router for React. In versions 6.4.0 through 7.17.0, if application code was written in a way that allows attacker-supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for an attacker to trigger unexpected constructor execution on the client, which would in turn trigger an outbound network request. This is only possible with very specific (and unlikely) application-layer code. Note that this does not impact an application if it is using Declarative Mode. It only impacts Framework Mode and Data Mode applications that perform manual SSR/hydration. This issue has been fixed in version 7.18.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-470",
              "description": "CWE-470: Use of Externally-Controlled Input to Select Classes or Code (\u0027Unsafe Reflection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-27T21:14:49.547Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg"
        },
        {
          "name": "https://github.com/remix-run/react-router/pull/15175",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/remix-run/react-router/pull/15175"
        },
        {
          "name": "https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a"
        },
        {
          "name": "https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180"
        },
        {
          "name": "https://github.com/remix-run/react-router/releases/tag/react-router@7.18.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/remix-run/react-router/releases/tag/react-router@7.18.0"
        }
      ],
      "source": {
        "advisory": "GHSA-337j-9hxr-rhxg",
        "discovery": "UNKNOWN"
      },
      "title": "React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-53666",
    "datePublished": "2026-07-27T21:14:49.547Z",
    "dateReserved": "2026-06-09T20:50:36.877Z",
    "dateUpdated": "2026-07-28T15:19:58.603Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-337J-9HXR-RHXG

CVE-2026-53666 (GCVE-0-2026-53666)

Tags

Sightings

Nomenclature