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Advisory severityMedium4.3Red Hat Linux

Medium [CVE-2026-14631] Denial of Service via malformed headers

This medium-severity Red Hat Linux advisory covers CVE-2026-14631.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-14631 Source published Source updated

VulniPulse record published Record updated

CVE-2026-14631
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

Summary

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.

Workarounds: keep the dev server bound to localhost (the default) and do not expose it to untrusted networks. This malformed input causes an uncaught exception, leading to the termination of the Node.js process and crashing the development server.

This vulnerability results in a Denial of Service (DoS), impacting the availability of the development server. webpack-dev-server is a development-time tool used to serve files during local frontend development and is not started or executed in production deployments.

While the package may appear in SBOM manifests due to its presence in build-stage node_modules, the webpack-dev-server process is not running in shipped container images or installed RPM packages, so the vulnerable code path (host/origin header validation) cannot be reached by an attacker in a production environment.

Red Hat severity: Moderate — CVSS 4.3 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Is CVE-2026-14631 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-14631 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-14631?

Upgrade to a fixed release named by Red Hat:

  • 5.2.5
  • 5.2.6

Confirm against the vendor advisory before you patch.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 11 days ago·verify at source

Fixed versions
  • 5.2.5
  • 5.2.6

Official advisory · high-confidence parse· fetched 11 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • webpack-dev-server should never be exposed to untrusted networks. By default, it binds to localhost only. Users who run webpack-dev-server during development should ensure it remains bound to localhost and upgrade to version 5.2.6 or later, which fixes the malformed header handling.

Official advisory · high-confidence parse· fetched 11 days ago·verify at source

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