TanStack router Cross-Site Scripting Flaw (CVE-2026-102989) Rated CVSS 9.3
A newly published critical vulnerability in TanStack router carries a CVSS score of 9.3. Here is what is affected and how to respond.
Key points
- CVE-2026-102989 affects TanStack router.
- CVSS 9.3 (Critical).
- No exploitation confirmed yet.
TanStack router is affected by CVE-2026-102989, a cross-site scripting that the National Vulnerability Database rates 9.3 out of 10.
At a glance
- CVE
- CVE-2026-102989
- Product
- TanStack router
- CVSS
- 9.3 Critical
- Weakness
- cross-site scripting
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: 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.
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| Tanstack | router | < release-2026-09-30-1747 |
| @Tanstack | react-start | >= 1.143.12, < 1.168.60 |
| @Tanstack | solid-start | >= 1.143.12, < 1.168.57 |
| @Tanstack | start-server-core | >= 1.143.12, < 1.169.39 |
| @Tanstack | vue-start | >= 1.143.12, < 1.168.56 |
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-102989
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-102989?
CVE-2026-102989 is a cross-site scripting vulnerability in TanStack router.
How severe is CVE-2026-102989?
It has a CVSS score of 9.3 Critical.
Is CVE-2026-102989 being exploited?
There is no public confirmation of exploitation at the time of publication.
