Vulnerability-Lookup

GHSA-QX66-FV34-FJM8

Vulnerability from github – Published: 2026-10-15 20:22 – Updated: 2026-10-15 20:22

Summary

TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses

Details

Impact

An unauthenticated attacker can craft a URL to a server function in an affected TanStack Start app. If someone opens the link, the app can return attacker-controlled HTML from its own origin and run the attacker's JavaScript there. The script can access same-origin data available to that visitor and make requests with their authority.

Cause

The server-function transport can pass request payload fields into internal middleware state instead of limiting them to public input fields. A malformed payload can leave an attacker-controlled result in the error path. Response handling can then treat a response-shaped object as an HTTP response.

Affected versions

Published versions of @tanstack/start-server-core, @tanstack/react-start, @tanstack/solid-start, and @tanstack/vue-start from 1.143.12 up to, but not including, their respective patched versions are affected. The patched versions are @tanstack/start-server-core@1.169.39, @tanstack/react-start@1.168.60, @tanstack/solid-start@1.168.57, and @tanstack/vue-start@1.168.56.

Fix

The fix limits client-supplied server-function input to public fields and validates responses at the server boundary. Upgrade to the corresponding patched package version.

Temporary mitigations

For the configured server-function path, usually /_serverFn/*, an edge or WAF rule can consider blocking requests without the literal x-tsr-serverFn: true header and browser document navigations such as Sec-Fetch-Mode: navigate or Accept: text/html. A restrictive Content Security Policy on server-function responses can provide another browser-side restriction. These are mitigation suggestions, not a complete fix. The header is client-controlled and is not authentication. Test rules against legitimate GET and POST server functions and use a matching version-specific backport where possible.

Credits

Lovable helped us discover and report this issue. We thank them for their help.

Severity

9.3 (Critical)


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

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@tanstack/start-server-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.143.12"
            },
            {
              "fixed": "1.169.39"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "@tanstack/react-start"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.143.12"
            },
            {
              "fixed": "1.168.60"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "@tanstack/solid-start"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.143.12"
            },
            {
              "fixed": "1.168.57"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "@tanstack/vue-start"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.143.12"
            },
            {
              "fixed": "1.168.56"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-102989"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-15T20:22:20Z",
    "nvd_published_at": "2026-10-13T17:17:14Z",
    "severity": "CRITICAL"
  },
  "details": "## Impact\n\nAn unauthenticated attacker can craft a URL to a server function in an affected TanStack Start app. If someone opens the link, the app can return attacker-controlled HTML from its own origin and run the attacker\u0027s JavaScript there. The script can access same-origin data available to that visitor and make requests with their authority.\n\n## Cause\n\nThe server-function transport can pass request payload fields into internal middleware state instead of limiting them to public input fields. A malformed payload can leave an attacker-controlled result in the error path. Response handling can then treat a response-shaped object as an HTTP response.\n\n## Affected versions\n\nPublished versions of `@tanstack/start-server-core`, `@tanstack/react-start`, `@tanstack/solid-start`, and `@tanstack/vue-start` from `1.143.12` up to, but not including, their respective patched versions are affected. The patched versions are `@tanstack/start-server-core@1.169.39`, `@tanstack/react-start@1.168.60`, `@tanstack/solid-start@1.168.57`, and `@tanstack/vue-start@1.168.56`.\n\n## Fix\n\nThe fix limits client-supplied server-function input to public fields and validates responses at the server boundary. Upgrade to the corresponding patched package version.\n\n## Temporary mitigations\n\nFor the configured server-function path, usually `/_serverFn/*`, an edge or WAF rule can consider blocking requests without the literal `x-tsr-serverFn: true` header and browser document navigations such as `Sec-Fetch-Mode: navigate` or `Accept: text/html`. A restrictive Content Security Policy on server-function responses can provide another browser-side restriction. These are mitigation suggestions, not a complete fix. The header is client-controlled and is not authentication. Test rules against legitimate GET and POST server functions and use a matching version-specific backport where possible.\n\n## Credits\n\nLovable helped us discover and report this issue. We thank them for their help.",
  "id": "GHSA-qx66-fv34-fjm8",
  "modified": "2026-10-15T20:22:21Z",
  "published": "2026-10-15T20:22:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/TanStack/router/security/advisories/GHSA-qx66-fv34-fjm8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102989"
    },
    {
      "type": "WEB",
      "url": "https://github.com/TanStack/router/pull/8573"
    },
    {
      "type": "WEB",
      "url": "https://github.com/TanStack/router/commit/d521abd71c69f1ff010bb3def4d417cb5fa058cb"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/TanStack/router"
    },
    {
      "type": "WEB",
      "url": "https://github.com/TanStack/router/releases/tag/release-2026-09-30-1747"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses"
}

CVE-2026-102989 (GCVE-0-2026-102989)

Vulnerability from cvelistv5 – Published: 2026-10-13 16:13 – Updated: 2026-10-14 15:20

Title

TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses

Summary

TanStack Router is a client-first, server-capable, fully type-safe router and full-stack framework for the web. From 1.143.12 until 1.169.39 for @tanstack/start-server-core, 1.168.60 for @tanstack/react-start, 1.168.57 for @tanstack/solid-start, and 1.168.56 for @tanstack/vue-start, an unauthenticated attacker can place non-public fields in a server-function request payload so that attacker-controlled middleware state reaches the error path and a response-shaped object is accepted as an HTTP response. A crafted server-function URL can therefore return attacker-controlled HTML from the application's origin; when a visitor opens the URL, the injected script can access same-origin data and issue requests with the visitor's authority. This issue is fixed in @tanstack/start-server-core 1.169.39, @tanstack/react-start 1.168.60, @tanstack/solid-start 1.168.57, and @tanstack/vue-start 1.168.56.

Severity

9.3 (Critical)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-14 15:19 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7926 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/TanStack/router/security/advis…	x_refsource_CONFIRM
https://github.com/TanStack/router/pull/8573	x_refsource_MISC
https://github.com/TanStack/router/commit/d521abd…	x_refsource_MISC
https://github.com/TanStack/router/releases/tag/r…	x_refsource_MISC

Impacted products

5 products

Vendor	Product	Version
TanStack	router	Affected: < release-2026-09-30-1747
@tanstack	react-start	Affected: >= 1.143.12, < 1.168.60
@tanstack	solid-start	Affected: >= 1.143.12, < 1.168.57
@tanstack	start-server-core	Affected: >= 1.143.12, < 1.169.39
@tanstack	vue-start	Affected: >= 1.143.12, < 1.168.56

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JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-102989",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-14T15:19:40.392223Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-14T15:20:08.563Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "router",
          "vendor": "TanStack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c release-2026-09-30-1747"
            }
          ]
        },
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          "product": "react-start",
          "vendor": "@tanstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.143.12, \u003c 1.168.60"
            }
          ]
        },
        {
          "product": "solid-start",
          "vendor": "@tanstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.143.12, \u003c 1.168.57"
            }
          ]
        },
        {
          "product": "start-server-core",
          "vendor": "@tanstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.143.12, \u003c 1.169.39"
            }
          ]
        },
        {
          "product": "vue-start",
          "vendor": "@tanstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.143.12, \u003c 1.168.56"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "TanStack Router is a client-first, server-capable, fully type-safe router and full-stack framework for the web. From 1.143.12 until 1.169.39 for @tanstack/start-server-core, 1.168.60 for @tanstack/react-start, 1.168.57 for @tanstack/solid-start, and 1.168.56 for @tanstack/vue-start, an unauthenticated attacker can place non-public fields in a server-function request payload so that attacker-controlled middleware state reaches the error path and a response-shaped object is accepted as an HTTP response. A crafted server-function URL can therefore return attacker-controlled HTML from the application\u0027s origin; when a visitor opens the URL, the injected script can access same-origin data and issue requests with the visitor\u0027s authority. This issue is fixed in @tanstack/start-server-core 1.169.39, @tanstack/react-start 1.168.60, @tanstack/solid-start 1.168.57, and @tanstack/vue-start 1.168.56."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-13T16:13:13.105Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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          "url": "https://github.com/TanStack/router/security/advisories/GHSA-qx66-fv34-fjm8"
        },
        {
          "name": "https://github.com/TanStack/router/pull/8573",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/TanStack/router/pull/8573"
        },
        {
          "name": "https://github.com/TanStack/router/commit/d521abd71c69f1ff010bb3def4d417cb5fa058cb",
          "tags": [
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          "url": "https://github.com/TanStack/router/commit/d521abd71c69f1ff010bb3def4d417cb5fa058cb"
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        {
          "name": "https://github.com/TanStack/router/releases/tag/release-2026-09-30-1747",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/TanStack/router/releases/tag/release-2026-09-30-1747"
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      "title": "TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses"
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    "dateReserved": "2026-09-29T20:46:08.334Z",
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    "state": "PUBLISHED"
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  "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.

Vulnerability timeline

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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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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