XSS in @Tanstack React-Start
CVE-2026-102989
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published .
CVSS v3 metric
CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- @Tanstack React-Start — versions >= 1.143.12, < 1.168.60
- @Tanstack Solid-Start — versions >= 1.143.12, < 1.168.57
- @Tanstack Start-Server-Core — versions >= 1.143.12, < 1.169.39
- @Tanstack Vue-Start — versions >= 1.143.12, < 1.168.56
- Tanstack Router — versions < release-2026-09-30-1747
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-102989?
- CVE-2026-102989 is a critical-severity vulnerability in @Tanstack React-Start, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2026-10-13.
- How severe is CVE-2026-102989?
- Critical severity. CVSS v3 base score is 9.3 out of 10.