CVE-2026-59896

hono/jsx does not isolate context per request, leading to cross-request data disclosure

Published

2026-07-21

Modified

2026-07-21

EPSS percentile

9%

Aliases

GHSA-hvrm-45r6-mjfj

Sources

github-advisory

Summary

### 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 of session or other request-scoped state

Affected packages

Remediation: Upgrade to 4.12.27 or later.

References

• https://github.com/advisories/GHSA-hvrm-45r6-mjfj