Affected: CleanStart: langfuse

CVE-2026-59896 affects multiple packages. This issue is resolved in later releases. See references for individual vulnerability details.

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.11.8 before 4.12.27, hono/jsx did not isolate context values per request during server-side rendering, allowing createContext, useContext, jsxRenderer, or useRequestContext data from a different in-flight request to be used after an await in an async component. This issue is fixed in version 4.12.27.

Affected: npm: hono

### Summary

`hono/jsx` did not isolate context values per request during server-side rendering. While an async component was suspended on `await`, its provided context value stayed observable to other requests rendering concurrently, so `useContext()` could return a value from a different in-flight request.

### Details

During server-side rendering, context values were kept in a process-wide structure rather than scoped to each request's render. While an async component awaited, another request entering the same provider could observe or replace the value; when the first render resumed, it could read the other request's context.

This affects the usual ways request-scoped data is passed through a server-rendered JSX tree:

- `createContext()` / `useContext()` - the `jsxRenderer` middleware and `useRequestContext()`

It arises only when context is read after an `await` inside an async component while requests render concurrently. Reading context synchronously (before any `await`), purely synchronous rendering, and client-side (DOM) rendering are not affected.

### Impact

Under concurrent requests, a response could be rendered with another request's context. A user may receive HTML rendered for a different user, and an authorization check performed after an `await` may be evaluated against another user's data.

This may lead to:

- disclosure of rendered output intended for another user - authorization decisions made with the wrong request's context - cross-request mixing o…