Vulnerability Details 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 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 6.0%
CVSS Severity
CVSS v3 Score 5.3
Products affected by CVE-2026-9595
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cpe:2.3:a:webpack.js:webpack-dev-server:1.10.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.10.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.11.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.12.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.12.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.13.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.14.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.14.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.15.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.15.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.15.2
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.2
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.3
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.4
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cpe:2.3:a:webpack.js:webpack-dev-server:1.16.5
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cpe:2.3:a:webpack.js:webpack-dev-server:1.7.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.8.0
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cpe:2.3:a:webpack.js:webpack-dev-server:1.8.1
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cpe:2.3:a:webpack.js:webpack-dev-server:1.8.2
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cpe:2.3:a:webpack.js:webpack-dev-server:1.9.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.0.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.1.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.10.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.10.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.11.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.11.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.11.2
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cpe:2.3:a:webpack.js:webpack-dev-server:2.11.3
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cpe:2.3:a:webpack.js:webpack-dev-server:2.2.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.2.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.3.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.2
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.3
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.4
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cpe:2.3:a:webpack.js:webpack-dev-server:2.4.5
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cpe:2.3:a:webpack.js:webpack-dev-server:2.5.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.5.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.6.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.6.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.7.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.7.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.8.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.8.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.8.2
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.0
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.1
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.2
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.3
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.4
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.5
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.6
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cpe:2.3:a:webpack.js:webpack-dev-server:2.9.7
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cpe:2.3:a:webpack.js:webpack-dev-server:3.0.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.0.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.10
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.11
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.12
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.13
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.14
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.2
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.3
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.4
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.5
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.6
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.7
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.8
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cpe:2.3:a:webpack.js:webpack-dev-server:3.1.9
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cpe:2.3:a:webpack.js:webpack-dev-server:3.10.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.10.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.10.2
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cpe:2.3:a:webpack.js:webpack-dev-server:3.10.3
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cpe:2.3:a:webpack.js:webpack-dev-server:3.11.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.11.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.11.2
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cpe:2.3:a:webpack.js:webpack-dev-server:3.11.3
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cpe:2.3:a:webpack.js:webpack-dev-server:3.2.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.2.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.3.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.3.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.4.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.4.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.5.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.5.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.6.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.7.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.7.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.7.2
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cpe:2.3:a:webpack.js:webpack-dev-server:3.8.0
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cpe:2.3:a:webpack.js:webpack-dev-server:3.8.1
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cpe:2.3:a:webpack.js:webpack-dev-server:3.8.2
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cpe:2.3:a:webpack.js:webpack-dev-server:3.9.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.0.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.1.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.1.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.10.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.10.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.11.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.11.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.12.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.13.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.13.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.13.2
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cpe:2.3:a:webpack.js:webpack-dev-server:4.13.3
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cpe:2.3:a:webpack.js:webpack-dev-server:4.14.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.15.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.15.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.15.2
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cpe:2.3:a:webpack.js:webpack-dev-server:4.2.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.2.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.3.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.3.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.4.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.5.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.6.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.7.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.7.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.7.2
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cpe:2.3:a:webpack.js:webpack-dev-server:4.7.3
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cpe:2.3:a:webpack.js:webpack-dev-server:4.7.4
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cpe:2.3:a:webpack.js:webpack-dev-server:4.8.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.8.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.9.0
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cpe:2.3:a:webpack.js:webpack-dev-server:4.9.1
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cpe:2.3:a:webpack.js:webpack-dev-server:4.9.2
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cpe:2.3:a:webpack.js:webpack-dev-server:4.9.3
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cpe:2.3:a:webpack.js:webpack-dev-server:5.0.0
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cpe:2.3:a:webpack.js:webpack-dev-server:5.0.1
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cpe:2.3:a:webpack.js:webpack-dev-server:5.0.2
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cpe:2.3:a:webpack.js:webpack-dev-server:5.0.3
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cpe:2.3:a:webpack.js:webpack-dev-server:5.0.4
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cpe:2.3:a:webpack.js:webpack-dev-server:5.1.0
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cpe:2.3:a:webpack.js:webpack-dev-server:5.2.0
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cpe:2.3:a:webpack.js:webpack-dev-server:5.2.1
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cpe:2.3:a:webpack.js:webpack-dev-server:5.2.2
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cpe:2.3:a:webpack.js:webpack-dev-server:5.2.3
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cpe:2.3:a:webpack.js:webpack-dev-server:5.2.4