How severe is CVE-2026-27148?

CVE-2026-27148 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-27148 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27148?

CVE-2026-27148 affects Storybook. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-27148?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-27148 have an EU (EUVD) identifier?

Yes. CVE-2026-27148 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8750.

When was CVE-2026-27148 published?

CVE-2026-27148 was published on 2026-02-25 and last updated on 2026-06-30.

CVE-2026-27148

CVE-2026-27148 is a critical-severity vulnerability in Storybook with a CVSS 3.x base score of 9.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.

Key facts

Severity: Critical (CVSS 3.x base score 9.6)
CVSS v4: 8.9
EPSS exploit prediction: 1% (42nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8750
Weakness: CWE-74
Affected product: Storybook
Published: 2026-02-25
Last modified: 2026-06-30

Description

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.

Frequently asked questions

What is CVE-2026-27148?: 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.
How severe is CVE-2026-27148?: CVE-2026-27148 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-27148 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27148?: CVE-2026-27148 affects Storybook. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-27148?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-27148 have an EU (EUVD) identifier?: Yes. CVE-2026-27148 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8750.
When was CVE-2026-27148 published?: CVE-2026-27148 was published on 2026-02-25 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:storybook:storybook:*:*:*:*:*:node.js:*:*

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