CVE-2026-114126 in Storybook
Summary
by MITRE • 10/21/2026
Storybook is a frontend workshop for building user interface components and pages in isolation. From 8.0.0 until 8.6.19, 9.1.21, 10.6.2, and 11.0.0-alpha.6, the Storybook development server can expose its WebSocket authentication token to clients able to load its HTML pages over a local network. A LAN attacker can obtain the token and invoke WebSocket-backed file-writing or testing functionality. Weak story-write validation can allow code to be placed in story files. If the Storybook Vitest addon is installed with an old version of Vitest, the payload can use a Vitest API to write additional files or execute commands. Depending on the payload and local tooling, the attack can lead to code execution with the developer's privileges. This issue is fixed in 8.6.19, 9.1.21, 10.6.2, and 11.0.0-alpha.6.
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Analysis
by VulDB Data Team • 10/22/2026
Storybook serves as a critical frontend workshop for developing user interface components and pages in isolation, facilitating efficient design system management and component testing within modern web development workflows. However, versions ranging from 8.0.0 through specific patches including 8.6.19, 9.1.21, 10.6.2, and 11.0.0-alpha.6 contain a significant security flaw related to the exposure of authentication tokens within its development server architecture. The vulnerability stems from an improper handling of WebSocket connections where the authentication token required for establishing secure communication channels is inadvertently exposed to any client capable of loading the Storybook HTML pages over a local area network. This design oversight allows attackers positioned on the same network segment to intercept or retrieve these credentials without requiring prior authentication, effectively bypassing intended access controls and granting unauthorized entry into the development environment's interactive features.
The operational impact of this vulnerability is severe due to the privileged nature of the exposed WebSocket functionality. Once an attacker obtains the valid authentication token, they can invoke backend operations that are typically restricted to trusted developers, such as file-writing capabilities or automated testing routines. The risk is further exacerbated by weak validation mechanisms within story-write processes, which permit malicious code injection into story files themselves. When combined with specific tooling configurations, particularly if an older version of the Vitest addon is installed alongside Storybook, this weakness becomes a direct pathway to remote code execution. An attacker can craft payloads that leverage vulnerable APIs provided by outdated testing libraries to write arbitrary files or execute system commands on the developer's machine, effectively compromising the integrity and security of the local development environment with the full privileges of the running user account.
This incident is classified under CWE-209 as an Information Exposure through an Error Message or Unprotected Channel, specifically involving sensitive data leakage via WebSocket connections. Furthermore, it aligns with MITRE ATT&CK techniques such as T1530 Data from Local System and potentially T1059 Command Line Interface if the payload results in command execution. The vulnerability highlights the dangers of exposing development server interfaces to untrusted network segments without robust authentication checks or token rotation mechanisms. To mitigate this risk, organizations must ensure that Storybook instances are not exposed on networks where unauthorized users might access them, ideally by binding the development server only to localhost or implementing strict firewall rules. Immediate remediation requires upgrading to patched versions 8.6.19, 9.1.21, 10.6.2, and 11.0.0-alpha.6 or later, which address these authentication flaws and strengthen validation logic for story file modifications. Additionally, developers should audit their dependency trees to ensure that testing addons like Vitest are updated to versions free from known API vulnerabilities that could be exploited in conjunction with this exposure.