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CVE-2026-14631

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

MEDIUM
5.3
CVSS Score
Published: July 3, 2026 at 05:23 PM UTC
Updated: July 7, 2026 at 03:23 PM UTC
2 products affected across 2 vendorsWebpack Dev ServerJs Webpack Dev Server

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Webpack Dev Server· Webpack Js
95%
v < 5.2.6
Affected range stops below 5.2.6, so it looks safe — our inference, not a vendor statement
Js Webpack Dev Server· Webpack Dev Server
60%
v < 5.2.6
Vendor states this is fixed in 5.2.6 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

MitigationVendor AdvisoryPatch
Source: cverecord
https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj
Third Party Advisory
Source: cverecord
https://cna.openjsf.org/security-advisories.html

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMopenjs
Vector?

Quick Info

StatusANALYZED
CWE
CWE-20CWE-248

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