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CVE Record

CVE-2026-27148: Storybook Dev Server Vulnerable to WebSocket Hijacking

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.

HighCVSS 8.9Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Storybook’s development server could accept browser-controlled WebSocket messages from the wrong origin. A developer visiting a malicious site while Storybook is running locally could have their workspace altered, with possible persistent XSS or RCE. Production Storybook builds are reported as not affected.

Executive priority

Prioritize remediation for teams exposing Storybook dev servers or using shared demos. For normal local-only development, urgency is lower but still important because compromise can affect source files and developer trust boundaries.

Technical view

The issue affects Storybook dev server WebSocket handlers for creating and saving stories. Missing origin validation allows WebSocket hijacking, and unsanitized componentFilePath input can lead to injection. Affected ranges are before 7.6.23, 8.6.17, 9.1.19, and 10.2.10.

Likely exposure

Exposure is most likely in developer workstations, shared design-review instances, CI preview systems, or demos running the Storybook dev server. Publicly exposed dev servers carry higher risk because attackers may connect directly without relying on a developer visiting a malicious site.

Exploitation context

The provided sources do not show KEV listing or confirmed active exploitation. Exploitation requires either user interaction with a malicious website while a local dev server is running, or direct network reachability to an exposed Storybook dev server.

Researcher notes

The key conditions are dev-server use, WebSocket origin validation failure, and vulnerable create/save story handlers. The bundle supports high severity and fixed versions, but does not provide active exploitation evidence or environment-specific vendor impacts beyond Storybook.

Mitigation direction

  • Upgrade Storybook to 7.6.23, 8.6.17, 9.1.19, 10.2.10, or later.
  • Do not expose Storybook dev servers to the public internet.
  • Restrict dev server access to trusted local or private networks.
  • Review vendor advisory and release notes for branch-specific upgrade guidance.
  • Treat exposed vulnerable instances as potentially compromised development environments.

Validation and detection

  • Inventory repositories and workstations for Storybook dependency versions.
  • Identify running Storybook dev servers and any public tunnels or preview URLs.
  • Confirm production builds are not being confused with dev server deployments.
  • Check package locks for affected version ranges listed in the advisory.
  • Review Storybook-created or modified story files for unexpected changes.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-346: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-74: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · medium confidence lookup

CWE-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-27148 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.9 (4.0)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.9CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H——GitHub_M
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:H2.85.3redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.9High
CVSS 4.0 vector shape for CVE-2026-27148Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPstorybook: Storybook: Remote Code Execution via WebSocket Hijacking
other:Red Hat severity ratingcvssV3_1
  • 2026-02-25T22:01:56.453Z: Reported to Red Hat.
  • 2026-02-25T21:46:48.967Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
storybookjsstorybook< 7.6.23, >= 8.1.0, < 8.6.17, >= 9.0.0, < 9.1.19, >= 10.0.0, < 10.2.10Listed
Weakness

CWE details

CWE-346CWE-74CWE-79

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.