GHSA-mjf5-7g4m-gx5w
Storybook Dev Server is Vulnerable to WebSocket Hijacking
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
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 | 8.6.17 |
| 📦npm | storybook | ≥ 8.7.0-alpha.0&&< 9.1.19 | 9.1.19 |
| 📦npm | storybook | ≥ 10.0.0-beta.0&&< 10.2.10 | 10.2.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for storybook. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update storybook to 8.6.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mjf5-7g4m-gx5w is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-mjf5-7g4m-gx5w is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-mjf5-7g4m-gx5w. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-mjf5-7g4m-gx5w in your dependencies?
O3 detects GHSA-mjf5-7g4m-gx5w across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.