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CVE-2026-9595

CVE-2026-9595 · webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 5.3 · Medium · EPSS 0.2% · Fix available

Published
Updated

Stack: system · node

Affected products and versions

  • webpack-dev-server

    Versions
    • ≥ 0, < 5.2.5: Affected (semver)
    • 5.2.5: Not affected (semver)

    Update to 5.2.5

  • webpack-dev-server npm

    Affected ranges
    • SEMVER: < 5.2.5

    Update to 5.2.5

  • node-webpack Ubuntu:18.04:LTS

    Versions
    • 3.5.6-1build3
    • 3.5.6-1build4
    • 3.5.6-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:20.04:LTS

    Versions
    • 4.7.0-3
    • 4.30.0-7
    • 4.30.0-9
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:20.04:LTS

    Versions
    • 2.5.17+dfsg-4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:22.04:LTS

    Versions
    • 4.43.0-6build4
    • 4.43.0-7
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:22.04:LTS

    Versions
    • 2.6.12+dfsg-3
    • 2.6.14+dfsg-1
    • 2.6.14+dfsg-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:24.04:LTS

    Versions
    • 5.76.1+dfsg1+~cs17.16.16-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:24.04:LTS

    Versions
    • 2.6.14+dfsg1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:25.10

    Versions
    • 5.97.1+dfsg1+~cs11.18.27-2
    • 5.97.1+dfsg1+~cs11.18.27-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:25.10

    Versions
    • 2.6.14+dfsg1-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:26.10

    Versions
    • 5.105.4+dfsg1+~cs15.13.23-2
    • 5.108.0+dfsg1+~cs14.7.20-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:26.10

    Versions
    • 2.6.14+dfsg1-3
    • 2.7.16+dfsg1-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-webpack Ubuntu:26.04:LTS

    Versions
    • 5.97.1+dfsg1+~cs11.18.27-3
    • 5.97.1+dfsg1+~cs11.18.27-4
    • 5.105.4+dfsg1+~cs15.13.23-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • vue.js Ubuntu:26.04:LTS

    Versions
    • 2.6.14+dfsg1-1
    • 2.6.14+dfsg1-1build1
    • 2.6.14+dfsg1-2
    • 2.6.14+dfsg1-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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