webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-112085
StatePUBLISHED
Assigneropenjs
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-22 10:17:08 UTC
Updated2026-10-22 10:17:08 UTC
Descriptionwebpack-dev-server is a development server that provides live reloading for webpack projects. In versions before 5.2.7 and in version 6.0.0, when a proxy entry is configured to forward WebSockets, the server forwards non-HMR WebSocket upgrade requests to the proxy target without validating the Host or Origin headers, so the allowedHosts protection does not apply to those proxied upgrades. A malicious web page visited by a developer can open a cross-origin WebSocket through the dev server and read from and write to the proxied backend, even when the server is bound to loopback. The issue is fixed in webpack-dev-server 5.2.7 and 6.1.0, where proxied WebSocket upgrades pass the same Host and Origin validation as the HMR WebSocket, and users should upgrade to one of those versions or later. As a workaround, omit WebSocket forwarding from proxy entries that do not need it and scope the proxy to specific paths.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from ce714d77-add3-4f53-aff5-83d477b104bb

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Problem Types: CWE-346 | CWE-1385 | CWE-346 CWE-346: Origin Validation Error | CWE-1385 CWE-1385: Missing Origin Validation in WebSockets

VersionSourceTypeScoreSeverityVector
3.1ce714d77-add3-4f53-aff5-83d477b104bbSecondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
3.1CNACVSS8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Webpack-dev-server Webpack-dev-server affected 5.2.7 semver Not specified
CNA Webpack-dev-server Webpack-dev-server unaffected 5.2.7 semver Not specified
CNA Webpack-dev-server Webpack-dev-server affected 6.0.0 6.1.0 semver Not specified
CNA Webpack-dev-server Webpack-dev-server unaffected 6.1.0 semver Not specified

References

ReferenceSourceLinkTags
github.com/webpack/webpack-dev-server/security/advisories/GHSA-cfqc-fj3v... ce714d77-add3-4f53-aff5-83d477b104bb github.com
cna.openjsf.org/security-advisories.html ce714d77-add3-4f53-aff5-83d477b104bb cna.openjsf.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: euriconicacio (en)

CNA: UlisesGascon (en)

CNA: bjohansebas (en)

CNA: alexander-akait (en)

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