CVE•Published 2026-06-15•Modified 2026-06-16•0 articles on news•5 live references•NVD data

CVE-2026-9595Webpack.js · Webpack-dev-server

Vulnerability data via NVD (ingested)

CVSS v3.1

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS percentile

—

Weaknesses (CWE)

CWE-346Origin Validation Error CWE-441Unintended Proxy or Intermediary ('Confused Deputy')

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.

Timeline

Published 2026-06-15

Modified 2026-06-16

External references

NVD MITRE Exploit-DB GitHub PoC VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-9595

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Webpack.js Webpack-dev-server"

All exposed Webpack.js Webpack-dev-server instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Webpack-dev-server"

HTTP body or banner mentions "Webpack-dev-server" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-9595