Executive brief
Hono is a web framework used to build fast applications. A flaw in its JSX component system could allow one user's private data to be accidentally shown to another user when the server is processing multiple requests at the same time. This could lead to unauthorized data exposure or incorrect security decisions if the system confuses which user is currently logged in.
Technical details
A race condition exists in the hono/jsx component during server-side rendering (SSR) where context values are stored in a process-wide structure rather than being scoped to individual requests. When an asynchronous component suspends on an 'await' call, its context value remains observable and can be overwritten by concurrent requests. An attacker or concurrent user could trigger a state where useContext() returns data belonging to a different in-flight request. This vulnerability specifically affects async components where context is read after an await; synchronous rendering and client-side rendering are unaffected. The issue is fixed in version 4.12.27.
Affected products
- honojs hono >= 4.11.8, < 4.12.27
Timeline
- 2026-06-23: disclosed: Vulnerability published to honojs/hono repository
- 2026-06-23: patched: Version 4.12.27 released
- 2026-07-08: advisory: NVD published CVE-2026-59896
- 2026-07-21: advisory: GitHub Advisory GHSA-hvrm-45r6-mjfj reviewed and updated
References
- https://api.github.com/users/thesmartshadow
- https://github.com/thesmartshadow
- https://api.github.com/users/thesmartshadow/gists%7B/gist_id%7D
- https://api.github.com/users/thesmartshadow/repos
- https://avatars.githubusercontent.com/u/33183887?v=4
- https://api.github.com/users/thesmartshadow/events%7B/privacy%7D