CVE-2026-9595

Impact: When a user-configured proxy on webpack-dev-server has a broad context (e.g. /) and ws: true, it also…

CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary 5.3 MEDIUMCVSS 3.1 · [email protected] · Primary 4.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

Historical advisory recorded 25 Oct 2026 16:19:28 UTC. Read the latest advisory.

nvd · CVE-2026-9595

Published

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 [email protected]. 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.

Read the publisher's advisory

Affected versions, risk and source history

nvd · CVE-2026-9595

Published

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 hea…

Additional publisher context

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Analyzed

Weakness classifications: CWE-346 · CWE-441

Original publisher date fields

published: 2026-06-15T16:16:35.227

lastModified: 2026-06-17T11:05:31.643

1 source CPE criteria · context only

cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*

The original JSON retains the logical configuration operators, exclusions and version bounds.

Source published: 15 Jun 2026 16:16:35 UTC
Source modified: 17 Jun 2026 11:05:31 UTC
Saved here: 25 Oct 2026 16:19:28 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS 3.1 · [email protected] · Primary · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L