webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies (webpack-dev-server webpack-dev-server)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.16 % · percentile 5 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- openjs
- NVD status
- Analyzed
Description
Impact: When a user-configured proxy on webpack-dev-server has a broad context (e.g. /) and ws: true, it also intercepts the dev server's own HMR WebSocket and forwards it to the proxy target. This leaks the browser's cookies and Origin header to the backend, bypasses the dev server's Host/Origin validation, and corrupts the HMR socket (both HMR and the proxy end up writing to the same socket). Patches: Fixed in webpack-dev-server@5.2.5. Workarounds: Scope user-defined proxy context to specific paths instead of /, or omit ws: true from the proxy entry when WebSocket forwarding is not required.
Weaknesses (CWE)
References
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-mx8g-39q3-5c79
- https://cna.openjsf.org/security-advisories.html
- https://github.com/webpack/webpack-dev-server/pull/4316
- https://github.com/vuejs/vue-cli/commit/72ba7505aff2a8314e82aa5082379a77504a1fcb
- https://github.com/facebook/create-react-app/pull/7444
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | openjs |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | NVD · ce714d77-add3-4f53-aff5-83d477b104bb (Secondary) |
| CVSS 3.1 | MEDIUM 4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-mx8g-39q3-5c79 — webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies
European references
- ENISA EUVD · EUVD-2026-36729
- GCVE · GCVE-0-2026-9595
CERT-FR advisories
- CERTFR-2026-AVI-1233 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*< 5.2.5
Affected products
| Product | Versions |
|---|---|
| webpack-dev-server · webpack-dev-server | affected 0 < 5.2.5 ; unaffected 5.2.5 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |