Access of Resource Using Incompatible Type ('Type Confusion') Affecting @tanstack/start-server-core package, versions <1.167.30
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- published15 May 2026
- disclosed14 May 2026
- creditUnknown
Introduced: 14 May 2026
New CVE NOT AVAILABLE CWE-502 (opens in a new tab)How to fix?
Upgrade @tanstack/start-server-core to version 1.167.30 or higher.
Overview
Affected versions of this package are vulnerable to Access of Resource Using Incompatible Type ('Type Confusion') through an upstream type-confusion bug in seroval package. An attacker can trigger unintended execution of a different client-referenced server function by sending a specially crafted JSON payload. This may result in unexpected side effects or bypass of request-level middleware, potentially impacting observability or audit logging.
Note:
The impact is limited to server functions that are already directly reachable _serverFn() function or the target function's full middleware chain — including any user-supplied authentication, authorization, and inputValidator.
Workaround
This vulnerability can be mitigated by ensuring that every exposed server function includes both input validation and authentication/authorization middleware.