{"id":"CVE-2026-102989","aliases":["EUVD-2026-98849","GHSA-qx66-fv34-fjm8"],"status":"published","title":"TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses","description":"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":{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00544,"percentile":0.46113,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-79"],"published":"2026-10-13T16:13:13Z","modified":"2026-10-28T02:30:56Z","fixes":[{"ecosystem":"npm","package":"@tanstack/start-server-core","fixed_in":["1.169.39"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@tanstack/react-start","fixed_in":["1.168.60"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@tanstack/solid-start","fixed_in":["1.168.57"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@tanstack/vue-start","fixed_in":["1.168.56"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@tanstack/start-server-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.143.12"},{"fixed":"1.169.39"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@tanstack/react-start","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.143.12"},{"fixed":"1.168.60"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@tanstack/solid-start","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.143.12"},{"fixed":"1.168.57"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@tanstack/vue-start","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.143.12"},{"fixed":"1.168.56"}]}]},{"source":"osv","ecosystem":"npm","package":"@tanstack/start-server-core","ranges":[{"type":"SEMVER","events":[{"introduced":"1.143.12"},{"fixed":"1.169.39"}]}]},{"source":"osv","ecosystem":"npm","package":"@tanstack/react-start","ranges":[{"type":"SEMVER","events":[{"introduced":"1.143.12"},{"fixed":"1.168.60"}]}]},{"source":"osv","ecosystem":"npm","package":"@tanstack/solid-start","ranges":[{"type":"SEMVER","events":[{"introduced":"1.143.12"},{"fixed":"1.168.57"}]}]},{"source":"osv","ecosystem":"npm","package":"@tanstack/vue-start","ranges":[{"type":"SEMVER","events":[{"introduced":"1.143.12"},{"fixed":"1.168.56"}]}]}],"products":[{"vendor":"@tanstack","product":"react-start"},{"vendor":"@tanstack","product":"solid-start"},{"vendor":"@tanstack","product":"start-server-core"},{"vendor":"@tanstack","product":"vue-start"},{"vendor":"asus","product":"router"},{"vendor":"tanstack","product":"router"}],"references":[{"url":"https://github.com/TanStack/router/security/advisories/GHSA-qx66-fv34-fjm8","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/TanStack/router/pull/8573","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/TanStack/router/commit/d521abd71c69f1ff010bb3def4d417cb5fa058cb","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/TanStack/router/releases/tag/release-2026-09-30-1747","tags":["x_refsource_MISC","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102989","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-qx66-fv34-fjm8"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102989.json","tags":["advisory"]},{"url":"https://github.com/TanStack/router","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-102989","title":"TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses","description":"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.","status":"published","published":"2026-10-13T16:13:13.105Z","modified":"2026-10-14T15:20:08.563Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical","assessor":"cna"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T13:38:54.394896Z"}],"euvd":[{"id":"EUVD-2026-98849","description":"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.","status":"published","published":"2026-10-13T16:13:13Z","modified":"2026-10-14T15:20:08Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T17:27:15.108271Z"}],"ghsa":[{"id":"GHSA-qx66-fv34-fjm8","title":"TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses","description":"## 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.","status":"published","published":"2026-10-15T20:22:20Z","modified":"2026-10-15T20:22:22Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:41:32.483482Z"}],"nvd":[{"id":"CVE-2026-102989","description":"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.","status":"published","published":"2026-10-13T17:17:14.797Z","modified":"2026-10-16T16:00:33.533Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical","assessor":"secondary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:12:57.132005Z"}],"osv":[{"id":"CVE-2026-102989","title":"TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses","description":"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.","status":"published","published":"2026-10-13T16:13:13.105Z","modified":"2026-10-28T02:30:56.55003521Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:44:54.236592Z"},{"id":"GHSA-qx66-fv34-fjm8","title":"TanStack Router: Unauthenticated reflected XSS in TanStack Start server-function responses","description":"## 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.","status":"published","published":"2026-10-15T20:22:20Z","modified":"2026-10-15T20:30:04.544571974Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:46:55.122811Z"}]}}