CVE-2026-27148 in storybook
Summary
by MITRE • 02/26/2026
Storybook is a frontend workshop for building user interface components and pages in isolation. Prior to versions 7.6.23, 8.6.17, 9.1.19, and 10.2.10, the WebSocket functionality in Storybook's dev server, used to create and update stories, is vulnerable to WebSocket hijacking. This vulnerability only affects the Storybook dev server; production builds are not impacted. Exploitation requires a developer to visit a malicious website while their local Storybook dev server is running. Because the WebSocket connection does not validate the origin of incoming connections, a malicious site can silently send WebSocket messages to the local instance without any further user interaction. If the Storybook dev server is intentionally exposed publicly (e.g. for design reviews or stakeholder demos) the risk is higher, as no malicious site visit is required. Any unauthenticated attacker can send WebSocket messages to it directly. The vulnerability affects the WebSocket message handlers for creating and saving stories. Both are vulnerable to injection via unsanitized input in the componentFilePath field, which can be exploited to achieve persistent XSS or Remote Code Execution (RCE). Versions 7.6.23, 8.6.17, 9.1.19, and 10.2.10 contain a fix for the issue.
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Analysis
by VulDB Data Team • 03/11/2026
Storybook serves as a powerful frontend development environment that enables developers to build user interface components in isolation while providing real-time preview capabilities through its development server. The vulnerability described in CVE-2026-27148 specifically targets the WebSocket communication layer within Storybook's development server implementation, creating a significant security risk for developers working in local environments. This weakness exists in versions prior to 7.6.23, 8.6.17, 9.1.19, and 10.2.10, where the WebSocket functionality lacks proper origin validation mechanisms that would normally prevent unauthorized connections from external sources.
The technical flaw stems from insufficient WebSocket origin validation within Storybook's development server implementation, which creates a WebSocket hijacking vulnerability classified under CWE-284 Access Control. When developers run Storybook's dev server locally, the WebSocket connections do not properly verify the origin of incoming messages, allowing malicious websites to establish unauthorized communication channels with the local server instance. This vulnerability operates through the WebSocket message handlers responsible for creating and saving stories, where the componentFilePath field accepts unsanitized input that can be exploited for injection attacks. The absence of input sanitization creates a direct pathway for attackers to manipulate the WebSocket communication flow and execute malicious commands.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables persistent cross-site scripting attacks and potentially full remote code execution capabilities. When a developer visits a malicious website while their local Storybook dev server is active, the attacker can silently send WebSocket messages that bypass normal user interaction requirements, making this particularly dangerous in development environments where developers frequently browse external sites. The vulnerability is especially severe when developers intentionally expose their local Storybook dev servers publicly for collaborative reviews or stakeholder demonstrations, as it eliminates the need for user interaction entirely. This scenario transforms the vulnerability from requiring social engineering to allowing immediate exploitation by any unauthenticated attacker who can access the exposed server.
The security implications of CVE-2026-27148 align with ATT&CK technique T1059 Command and Scripting Interpreter, where attackers can execute malicious code through the WebSocket injection vectors. The vulnerability also relates to ATT&CK technique T1190 Exploit Public-Facing Application, as it affects publicly exposed development servers and can be exploited by remote attackers without requiring local system access. Organizations using Storybook in development environments must consider the risk of compromised development machines leading to broader security incidents, as the attack surface extends from simple XSS to potential RCE capabilities. The fix implemented in versions 7.6.23, 8.6.17, 9.1.19, and 10.2.10 addresses the core WebSocket origin validation issue and includes proper input sanitization for the componentFilePath field, effectively closing the attack vectors that enabled the exploitation of this vulnerability.