CVE-2026-14631

webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header

CVSS 3.1 5.3 MEDIUMEUVD CVSS 3.1 5.3 CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary 5.3 MEDIUMCVSS_V3 Publisher rating MODERATEFixed by webpack-dev-server 5.2.6KEV status unknown

Original advisory

cve-program · CVE-2026-14631

Published

webpack-dev-server versions 5.2.5 and earlier terminate the whole Node.js process when an unauthenticated peer sends either a normal HTTP request with a malformed Host header or a WebSocket upgrade to the default /ws endpoint with a malformed Origin header. The malformed value causes an uncaught exception in the host-validation path and crashes the dev server. Impact is limited to availability of the development server, no data disclosure, no code execution. Patches: upgrade to webpack-dev-server 5.2.6. Workarounds: keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.

Read the publisher's advisory

euvd · EUVD-2026-41559

Published

Read the publisher's advisory

nvd · CVE-2026-14631

Published

Read the publisher's advisory

osv · GHSA-m28w-2pqf-7qgj

Published

### Impact An unauthenticated peer that can reach the `webpack-dev-server` process can terminate it by sending either a normal HTTP request with a malformed `Host` header, or a WebSocket upgrade to the default `/ws` endpoint with a malformed `Origin` header. The malformed header triggers an uncaught exception in the host-validation path and crashes the dev server process. ### Patches Fixed in `webpack-dev-server` 5.2.6 by treating malformed `Host` and `Origin` header values as invalid rather than throwing (see [PR #5699](https://github.com/webpack/webpack-dev-server/pull/5699)). ### Workarounds Keep the dev server bound to `localhost` (the default) and do not expose it to untrusted networks.

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Affected versions, risk and source history

cve-program · CVE-2026-14631

Published

webpack-dev-server

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "webpack-dev-server",
                    "product": "webpack-dev-server",
                    "defaultStatus": "unaffected",
                    "versions": [
                        {
                            "versionType": "semver",
                            "status": "affected",
                            "version": "0",
                            "lessThan": "5.2.6"
                        },
                        {
                            "versionType": "semver",
                            "status": "unaffected",
                            "version": "5.2.6"
                        }
                    ],
                    "packageURL": "pkg:npm/webpack-dev-server"
                }

Original source record · Cite this exact observation · Complete original publisher JSON

euvd · EUVD-2026-41559

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Jul 3, 2026, 5:23:41 PM

dateUpdated: Jul 6, 2026, 3:54:11 PM

No normalized affected-package data is projected for this source revision. The original publisher record may contain additional product and version evidence; this does not establish that a package is unaffected.

Original source record · Cite this exact observation · Complete original publisher JSON

nvd · CVE-2026-14631

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Analyzed

Weakness classifications: CWE-20 · CWE-248

Original publisher date fields

published: 2026-07-03T18:16:24.687

lastModified: 2026-07-07T15:08:59.667

1 source CPE criteria · context only

cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*

The original JSON retains the logical configuration operators, exclusions and version bounds.

Original source record · Cite this exact observation · Complete original publisher JSON

osv · GHSA-m28w-2pqf-7qgj

Published

webpack-dev-server

npm

SEMVER · introduced 0 → fixed 5.2.6

Original source record · Cite this exact observation · Complete original publisher JSON