storybook: Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2026-27148 is a critical-severity improper neutralization of special elements in output used by a downstream component vulnerability in storybook from Storybookjs, with a CVSS 3.1 base score of 9.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected storybook versions: < 7.6.23; >= 8.1.0, < 8.6.17; >= 9.0.0, < 9.1.19, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of storybook you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Storybookjs | storybook | < 7.6.23; >= 8.1.0, < 8.6.17; >= 9.0.0, < 9.1.19; >= 10.0.0, < 10.2.10 | Not stated |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | streams for Apache Kafka 2 | Not specified in the record | Not stated |
| Red Hat | streams for Apache Kafka 3 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.9 | High | CNA (github.com) |
| CVSS 3.1 | 9.6 | Critical | NVD |
| CVSS 3.1 | 8.8 | High | CNA |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements in Output Used by a Downstream Component
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How developers prevent this class of flaw
- Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/storybookjs/storybook/commit/0affdf928bd6fafbadfb1dfe22ce6104805e10e8
- github.com/storybookjs/storybook/commit/54689a8add18ea75d628c540f4bc677592a1e685
- github.com/storybookjs/storybook/commit/b8cfa77c73940c140acdcd8a06ab1ea913c44761
- github.com/storybookjs/storybook/commit/d34085f39c647f5c23c3a3b2d197c18602fcf876
- github.com/storybookjs/storybook/releases/tag/v10.2.10Release Notes
- github.com/storybookjs/storybook/releases/tag/v7.6.23Release Notes
- github.com/storybookjs/storybook/releases/tag/v8.6.17Release Notes
- github.com/storybookjs/storybook/releases/tag/v9.1.19Release Notes
Other references
Other vulnerabilities in storybook
- 8.7 High severity
- 8.6 High severity
Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities
- 7.3 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.1 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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