CVE-2026-27148CWE-74CWE-79

Storybook Dev Server Vulnerable to WebSocket Hijacking

High · published February 25, 2026

CVSS v4.0
8.9
EPSS
1%
Percentile
49.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.9 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
EPSS
0.00620 · 49.0th percentile
Weaknesses
CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'); CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-02-25T21:46Z
EPSS history
Timeline
  • 25 FEB 21:46Z
    Storybook Dev Server Vulnerable to WebSocket Hijacking
    cvelistv5