webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header
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).
Workarounds
Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | webpack-dev-server | < 5.2.6 | 5.2.6 |
References
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj
- https://nvd.nist.gov/vuln/detail/CVE-2026-14631
- https://github.com/webpack/webpack-dev-server/pull/5699
- https://github.com/webpack/webpack-dev-server/commit/f21ed0f44aceb6132abb591ee8b60d770b6e489f
- https://cna.openjsf.org/security-advisories.html
- https://github.com/webpack/webpack-dev-server
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-20, CWE-248- Platform
- npm
- Package
webpack-dev-server- Disclosed
- 20.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-m28w-2pqf-7qgj - CC BY 4.0
Vulnerability history: webpack-dev-server
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 01.2019 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 6
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 2
- 2026: 4
-
webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header this entry
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