CVE-2026-27148 — storybook
Fix: storybookjs/storybook@0affdf9CVE-2026-27148 is a CWE-74 vulnerability in storybook. A fix is available for storybook — see the affected versions and patch details below.
Storybook Dev Server Vulnerable to WebSocket Hijacking
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-27148.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
storybooknpmDescription
Summary
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.
Details
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 a 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, which can be exploited via unauthorized WebSocket connections to achieve persistent XSS or Remote Code Execution (RCE).
Note: recent versions of Chrome have some protections against this, but Firefox does not.
Impact
This vulnerability can lead to supply chain compromise. Key risks include:
- Remote Code Execution: The vulnerability can allow attackers to execute malicious code, with the extent of impact depending on the configuration. Server-side RCE is possible in non-default configurations, such as when stories are executed via portable stories in JSDOM, potentially allowing attackers to exfiltrate credentials and environment variables, access source code and the filesystem, establish backdoors, or pivot to internal network resources.
- Persistent XSS: Malicious payloads are written directly into story source files. If the malicious payload is committed to version control, it becomes part of the codebase and can propagate to deployed Storybook documentation sites, affecting developers and stakeholders who view them.
- Supply Chain Propagation: If the modified source files are committed, injected code can spread to other team members via git, execute in CI/CD pipelines, and affect shared component libraries used across multiple projects.
Affected versions
8.1 and above. While the exploitable functionality was introduced in 8.1, the patch has been applied to 7.x as a precautionary measure given the underlying WebSocket behaviour.
Recommended actions
Update to one of the patched versions: 7.6.23, 8.6.17, 9.1.19, 10.2.10.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | storybook | ≥ 8.1.0&&< 8.6.17 | 8.6.17npm install storybook@8.6.17 |
| 📦npm | storybook | ≥ 8.7.0-alpha.0&&< 9.1.19 | 9.1.19npm install storybook@9.1.19 |
| 📦npm | storybook | ≥ 10.0.0-beta.0&&< 10.2.10 | 10.2.10npm install storybook@10.2.10 |
Affected Products
storybookstorybookDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for storybook, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update storybook to 8.6.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-27148 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2026-27148 in your dependencies?
Find it across npm, including transitive dependencies.