Storybook: Missing origin validation in Storybook preview allows code injection from malicious websites

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-114125: 0.39% estimated exploitation activity in the next 30 days; percentile 32.61 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary: A malicious website may be able to cause unauthorized file changes in a developer’s project while an affected Storybook development server is running. Under additional conditions, a changed file could be executed by a local runtime with the developer’s privileges. We are not aware of exploitation in the wild. Who is impacted? You are impacted if you run a Storybook dev server in the affected versions. You are not impacted if: - You run a dev server that you never open in a web browser (e.g. headless automation, MCP clients) - You run or visit a built version of Storybook Recent versions of Chrome and Firefox may ask for permission before a website can connect to a localhost service. This reduces the risk, but does not remove it. Do not grant this permission to websites you don’t trust. Recommended actions Upgrade Storybook Storybook has released patched versions of all affected major Storybook versions that fix all the vulnerabilities necessary for the worst-case scenario…

Published by the source

21 Oct 2026, 17:23 UTC

Last modified by the source

21 Oct 2026, 17:35 UTC

Source last checked

26 Oct 2026, 13:07 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-f2ph-cmg5-wxc8

2. Revision 3 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-f2ph-cmg5-wxc8

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-f2ph-cmg5-wxc8

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-114125

Advisory: Storybook: Missing origin validation in Storybook preview allows code injection from malicious websites
IDs: CVE-2026-114125, GHSA-f2ph-cmg5-wxc8
Record: https://patchnext.com/advisories/cve-2026-114125 (revision 4, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: storybook 11.0.0-alpha.6, 10.6.2, 9.1.21, 8.6.19; @storybook/core 8.6.19; @storybook/experimental-addon-test 8.6.19; @storybook/core-server 8.6.19; @storybook/addon-vitest 11.0.0-alpha.6, 10.6.2, 9.1.21; @storybook/addon-mcp 11.0.0-alpha.6, 10.6.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm storybook: affected >= 8.0.0, < 8.6.19; >= 9.0.0, < 9.1.21; >= 10.0.0, < 10.6.2; >= 11.0.0-alpha.0, < 11.0.0-alpha.6; fixed in 11.0.0-alpha.6, 8.6.19, 10.6.2, 9.1.21
- npm @storybook/core: affected >= 8.0.0, < 8.6.19; fixed in 8.6.19
- npm @storybook/experimental-addon-test: affected >= 8.0.0, < 8.6.19; fixed in 8.6.19
- npm @storybook/core-server: affected >= 8.0.0, < 8.6.19; fixed in 8.6.19
- npm @storybook/addon-vitest: affected >= 9.0.0, < 9.1.21; >= 10.0.0, < 10.6.2; >= 11.0.0-alpha.0, < 11.0.0-alpha.6; fixed in 11.0.0-alpha.6, 10.6.2, 9.1.21
- npm @storybook/addon-mcp: affected >= 10.6.0, < 10.6.2; >= 11.0.0-alpha.0, < 11.0.0-alpha.6; fixed in 11.0.0-alpha.6, 10.6.2

## Suggested inspection (read-only)
- `npm ls storybook --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @storybook/core --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @storybook/experimental-addon-test --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @storybook/core-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @storybook/addon-vitest --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls @storybook/addon-mcp --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on storybook, @storybook/core, @storybook/experimental-addon-test, @storybook/core-server, @storybook/addon-vitest, @storybook/addon-mcp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f2ph-cmg5-wxc8 (GitHub-reviewed advisory GHSA-f2ph-cmg5-wxc8 lists affected ranges: npm storybook >=8.0.0 =9.0.0 =10.0.0 =11.0.0-alpha.0 =8.0.0 =8.0.0 =8.0.0 =9.0.0 =10.0.0 =11.0.0-alpha.0 =10.6.0 =11.0.0-alpha.0 <11.0.0-alpha.6)
- Verified: https://osv.dev/vulnerability/GHSA-f2ph-cmg5-wxc8 (OSV record GHSA-f2ph-cmg5-wxc8 lists affected ranges: npm storybook >=8.0.0 =9.0.0 =10.0.0 =11.0.0-alpha.0 =8.0.0 =8.0.0 =8.0.0 =9.0.0 =10.0.0 =11.0.0-alpha.0 <11.0.0-alpha.6 (fixed); npm @storybook/addon-mcp…)

Commands are suggestions: review each one before running it.