Vulnerability in Webpack-dev-server
CVE-2026-9595
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 he…
EPSS: 0.002 (5.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
Affected products
- Webpack-dev-server — versions 0, 5.2.5
- Webpack.js Webpack-dev-server
Weakness classification (CWE)
References
- ce714d77-add3-4f53-aff5-83d477b104bb (Mitigation, Vendor Advisory)
- ce714d77-add3-4f53-aff5-83d477b104bb (Vendor Advisory)
- ce714d77-add3-4f53-aff5-83d477b104bb (Patch, Issue Tracking)
- ce714d77-add3-4f53-aff5-83d477b104bb (Patch)
- ce714d77-add3-4f53-aff5-83d477b104bb (Patch, Issue Tracking)
Frequently asked questions
- What is CVE-2026-9595?
- CVE-2026-9595 is a medium-severity vulnerability in Webpack-dev-server, classified under Origin Validation Error. CVSS score: 5.3/10. Published 2026-06-15.
- How severe is CVE-2026-9595?
- Medium severity. CVSS v3 base score is 5.3 out of 10.