Vulnerabilities in pkg:npm/@tanstack/start-server-core

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qx66-fv34-fjm8",
  "modified" : "2026-10-15T20:22:21Z",
  "published" : "2026-10-15T20:22:20Z",
  "aliases" : [ "CVE-2026-102989" ],
  "summary" : "TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses",
  "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's 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@tanstack/start-server-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.143.12"
      }, {
        "fixed" : "1.169.39"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@tanstack/react-start"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.143.12"
      }, {
        "fixed" : "1.168.60"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@tanstack/solid-start"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.143.12"
      }, {
        "fixed" : "1.168.57"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@tanstack/vue-start"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.143.12"
      }, {
        "fixed" : "1.168.56"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-15T20:22:20Z",
    "nvd_published_at" : "2026-10-13T17:17:14Z"
  }
}