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

{
  "id": "5017b8b3e390bfdc8f51e4f9c9f504366521b3c7ff69b111bfd99429ed83a09f",
  "url": "https://osv.dev/vulnerability/GHSA-qx66-fv34-fjm8",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses",
    "summary": "## 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: navigat",
    "evidence": "osv:GHSA-qx66-fv34-fjm8",
    "products": [
      {
        "name": {
          "value": "@tanstack/start-server-core",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.169.39",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@tanstack/react-start",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.168.60",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@tanstack/solid-start",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.168.57",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@tanstack/vue-start",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.168.56",
            "evidence": "/affected/3/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "GHSA-qx66-fv34-fjm8",
      "aliases": [
        "CVE-2026-102989",
        "GHSA-qx66-fv34-fjm8"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.143.12"
                },
                {
                  "fixed": "1.169.39"
                }
              ]
            }
          ],
          "package": {
            "name": "@tanstack/start-server-core",
            "purl": "pkg:npm/%40tanstack/start-server-core",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qx66-fv34-fjm8/GHSA-qx66-fv34-fjm8.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.143.12"
                },
                {
                  "fixed": "1.168.60"
                }
              ]
            }
          ],
          "package": {
            "name": "@tanstack/react-start",
            "purl": "pkg:npm/%40tanstack/react-start",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qx66-fv34-fjm8/GHSA-qx66-fv34-fjm8.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.143.12"
                },
                {
                  "fixed": "1.168.57"
                }
              ]
            }
          ],
          "package": {
            "name": "@tanstack/solid-start",
            "purl": "pkg:npm/%40tanstack/solid-start",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qx66-fv34-fjm8/GHSA-qx66-fv34-fjm8.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.143.12"
                },
                {
                  "fixed": "1.168.56"
                }
              ]
            }
          ],
          "package": {
            "name": "@tanstack/vue-start",
            "purl": "pkg:npm/%40tanstack/vue-start",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qx66-fv34-fjm8/GHSA-qx66-fv34-fjm8.json"
          }
        }
      ],
      "modified": "2026-10-15T20:30:04.544571974Z",
      "provider": "osv",
      "references": [
        "https://github.com/TanStack/router/security/advisories/GHSA-qx66-fv34-fjm8",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-102989",
        "https://github.com/TanStack/router/pull/8573",
        "https://github.com/TanStack/router/commit/d521abd71c69f1ff010bb3def4d417cb5fa058cb",
        "https://github.com/TanStack/router",
        "https://github.com/TanStack/router/releases/tag/release-2026-09-30-1747"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "severity": "CRITICAL",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-13T17:17:14Z",
        "github_reviewed_at": "2026-10-15T20:22:20Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-102989",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 336041,
  "published_at": "2026-10-15T20:22:20+00:00"
}