CVE-2026-59896 in hono
Summary
by MITRE • 07/08/2026
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.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/08/2026
The vulnerability in Hono.js affects versions 4.11.8 through 4.12.26 where the jsx rendering functionality fails to properly isolate context values between individual requests during server-side rendering operations. This design flaw creates a critical race condition scenario where asynchronous components can inadvertently access or modify data from other concurrent requests that are in-flight. The issue specifically impacts the createContext, useContext, jsxRenderer, and useRequestContext APIs which are fundamental to managing shared state within the framework's rendering pipeline.
The technical root cause stems from improper request context management within the server-side rendering process. When an async component encounters an await statement during execution, the runtime may switch to a different request's context if proper isolation mechanisms are not implemented. This occurs because the framework does not maintain separate execution contexts for each incoming HTTP request, allowing shared mutable state to be corrupted or contaminated by concurrent operations. The vulnerability manifests when multiple requests are processed simultaneously and one request's async operations overlap with another's execution timeline.
The operational impact of this vulnerability extends beyond simple data corruption to potentially enable cross-request information leakage and unauthorized data access patterns. An attacker could exploit this weakness to retrieve sensitive context data belonging to other users or sessions, particularly in multi-tenant applications where isolation between requests is paramount. The vulnerability affects any application using Hono's jsx rendering capabilities with async components, making it a widespread concern across implementations that rely on server-side rendering for dynamic content generation.
This issue aligns with CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) vulnerabilities and improper context isolation in concurrent environments. The problem also relates to ATT&CK technique T1595.001 concerning credential access through shared resources and T1211 which involves exploitation of race conditions. Organizations using Hono.js versions within the affected range should immediately implement mitigation strategies including upgrading to version 4.12.27 or later, implementing additional request context validation layers, and monitoring for unauthorized data access patterns in their server-side rendering operations.
The fix implemented in version 4.12.27 addresses the core issue by introducing proper request-scoped context isolation during async component execution. This ensures that each HTTP request maintains its own isolated execution environment regardless of concurrent processing or await operations within jsx components. The remediation follows security best practices for concurrent application frameworks and aligns with industry standards for preventing context contamination in multi-request environments, effectively closing the vulnerability window that allowed cross-request data leakage through improper state management during server-side rendering processes.