CVE-2026-114125: Storybook: Missing origin validation in Storybook preview allows code injection from malicious websites

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
• Only applies if your dependency tree includes storybook (npm) >= 8.0.0, < 8.6.19, fixed in 8.6.19; storybook (npm) >= 9.0.0, < 9.1.21, fixed in 9.1.21; storybook (npm) >= 10.0.0, < 10.6.2, fixed in 10.6.2; storybook (npm) >= 11.0.0-alpha.0, < 11.0.0-alpha.6, fixed in 11.0.0-alpha.6. Check your lockfile, including transitive dependencies.

What it is

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, a malicious website can interact with the preview of a running Storybook development server. Insufficient iframe embedding and message-origin restrictions can allow attacker-controlled events to reach the running preview. A developer must visit the malicious website and interact with the injected interface. The attack can cause unauthorized changes to story files and, if a changed file is later executed by a local runtime, arbitrary 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.

From the GitHub advisory

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

Weakness type: CWE-94, CWE-346, CWE-1021, CWE-22, CWE-96.

Product: storybook (npm) · Assigned by: GitHub_M · Published: 2026-10-21

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: active

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).

Timeline

• 2026-10-21 — CVE record last updated
• 2026-10-21 — CVE record published by GitHub_M
• 2026-10-21 — GitHub-reviewed advisory GHSA-f2ph-cmg5-wxc8 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-f2ph-cmg5-wxc8 github.com
2. CVE.org record CVE-2026-114125 cve.org
3. NVD entry CVE-2026-114125 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
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