{"id":"CVE-2026-9595","summary":"webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies","details":"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).\n\nPatches: Fixed in webpack-dev-server@5.2.5.\n\nWorkarounds: Scope user-defined proxy context to specific paths instead of /, or omit ws: true from the proxy entry when WebSocket forwarding is not required.","aliases":["GHSA-mx8g-39q3-5c79"],"modified":"2026-07-08T08:12:41.313421826Z","published":"2026-06-15T15:00:21.488Z","related":["CGA-vv36-83jw-hjff"],"database_specific":{"cna_assigner":"openjs","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9595.json","cwe_ids":["CWE-346","CWE-441"]},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9595.json"},{"type":"ADVISORY","url":"https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-mx8g-39q3-5c79"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-9595"},{"type":"FIX","url":"https://github.com/facebook/create-react-app/pull/7444"},{"type":"FIX","url":"https://github.com/vuejs/vue-cli/commit/72ba7505aff2a8314e82aa5082379a77504a1fcb"},{"type":"FIX","url":"https://github.com/webpack/webpack-dev-server/pull/4316"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/vuejs/vue-cli","events":[{"introduced":"0"},{"fixed":"72ba7505aff2a8314e82aa5082379a77504a1fcb"}],"database_specific":{"source":"REFERENCES"}},{"type":"GIT","repo":"https://github.com/webpack/webpack-dev-server","events":[{"introduced":"0"},{"fixed":"c3ee325819f64ceb77f85dcf727b6b5ede85cbc4"}],"database_specific":{"cpe":"cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*","source":["AFFECTED_FIELD","CPE_RANGE"],"extracted_events":[{"introduced":"0"},{"fixed":"5.2.5"}]}}],"versions":["v4.0.0-rc.1","v4.0.0-rc.0","v4.0.0-beta.3","v4.0.0-beta.2","v4.0.0-beta.1","v4.0.0-beta.0","v4.0.0-alpha.5","v4.0.0-alpha.4","v4.0.0-alpha.3","v4.0.0-alpha.2","v4.0.0-alpha.1","v3.7.0","v4.0.0-alpha.0","v3.6.3","v3.6.2","v3.6.1","v3.5.1","vue-cli-version-marker@3.3.0","v3.3.0","v3.2.3","vue-cli-version-marker@3.2.2","v3.2.2","v3.2.1","v3.2.0","@vue/eslint-config-typescript@3.2.0","vue-cli-version-marker@3.1.2","@vue/cli@3.1.3","vue-cli-version-marker@3.1.1","@vue/eslint-config-prettier@4.0.1","@vue/cli@3.1.2","@vue/cli-ui@3.1.2","@vue/cli-ui-addon-widgets@3.1.2","@vue/cli-ui-addon-webpack@3.1.2","@vue/cli-service@3.1.4","@vue/cli-service-global@3.1.3","@vue/cli-plugin-pwa@3.1.2","@vue/cli-plugin-eslint@3.1.5","@vue/cli-plugin-e2e-cypress@3.1.2","@vue/cli-plugin-babel@3.1.1","@vue/eslint-config-typescript@3.1.1","@vue/cli@3.1.1","@vue/cli-upgrade@3.1.1","@vue/cli-ui@3.1.1","@vue/cli-ui-addon-widgets@3.1.1","@vue/cli-ui-addon-webpack@3.1.1","@vue/cli-test-utils@3.1.1","@vue/cli-shared-utils@3.1.1","@vue/cli-service@3.1.2","@vue/cli-service-global@3.1.2","@vue/cli-plugin-unit-mocha@3.1.1","@vue/cli-plugin-unit-jest@3.1.1","@vue/cli-plugin-typescript@3.1.1","@vue/cli-plugin-pwa@3.1.1","@vue/cli-plugin-eslint@3.1.4","@vue/cli-plugin-e2e-nightwatch@3.1.1","@vue/cli-plugin-e2e-cypress@3.1.1","@vue/cli-init@3.1.1","@vue/cli-plugin-eslint@3.1.3","@vue/cli-plugin-eslint@3.1.2","v3.1.1","v3.0.5","v3.0.4","v3.0.3","v3.0.2","v3.0.1","v3.0.0","v3.0.0-rc.12","v3.0.0-rc.11","v3.0.0-rc.10","v3.0.0-rc.9","v3.0.0-rc.8","v3.0.0-rc.7","v3.0.0-rc.6","v3.0.0-rc.5","v3.0.0-rc.4","v3.0.0-rc.3","v3.0.0-rc.2","v3.0.0-rc.1","v3.0.0-beta.16","v3.0.0-beta.15","v3.0.0-beta.12","v3.0.0-beta.3","v3.0.0-beta.2","v3.0.0-beta.1","v3.0.0-alpha.13","v3.0.0-alpha.12","v3.0.0-alpha.11","v3.0.0-alpha.10","v3.0.0-alpha.9","v3.0.0-alpha.8","v3.0.0-alpha.7","v3.0.0-alpha.6","v3.0.0-alpha.5","v3.0.0-alpha.4","v3.0.0-alpha.3","v3.0.0-alpha.2","v3.0.0-alpha.1","v5.2.4","v5.2.3","v5.2.2","v5.2.1","v5.2.0","v5.1.0","v5.0.4","v4.15.1","v5.0.3","v5.0.2","v5.0.1","v5.0.0","v4.15.0","v4.14.0","v4.13.3","v4.13.2","v4.13.1","v4.13.0","v4.12.0","v4.11.1","v4.11.0","v4.10.1","v4.10.0","v4.9.3","v4.9.2","v4.9.1","v4.9.0","v4.8.1","v4.8.0","v4.7.4","v4.7.3","v4.7.2","v4.7.1","v4.7.0","v4.6.0","v4.5.0","v4.4.0","v4.3.1","v4.3.0","v4.2.1","v4.2.0","v4.1.1","v4.1.0","v4.0.0","v3.11.0","v3.10.3","v3.10.2","v3.10.0","v3.9.0","v3.8.2","v3.8.1","v3.8.0","v3.7.2","v3.7.1","v3.5.0","v3.4.1","v3.4.0","v3.3.1","v3.1.14","v3.1.13","v3.1.12","v3.1.11","v3.1.10","v3.1.9","v3.1.8","v3.1.7","v3.1.6","v3.1.5","v3.1.4","v3.1.3","v3.1.2","v3.1.0","v3.0.1-beta.0","v2.11.1","v2.11.0","v2.10.1","v2.10.0","v2.9.7","v2.9.6","v2.9.5","v2.9.3","v2.9.2","v2.9.1","v2.9.0","v2.8.2","v2.8.1","v2.8.0","v2.6.1","v2.6.0","v2.5.0","v2.4.5","v2.4.4","v2.4.3","v2.4.2","v2.4.1","v2.4.0","v2.3.0","v2.2.1","v2.2.0","v2.2.0-rc.0","v2.1.0-beta.12","v2.1.0-beta.11","v2.1.0-beta.10","v2.1.0-beta.9","v2.1.0-beta.8","v2.1.0-beta.7","v2.1.0-beta.6","v2.1.0-beta.5","v2.1.0-beta.4","v2.1.0-beta.3","v2.1.0-beta.2","v2.1.0-beta.1","v2.1.0-beta.0","v2.0.0-beta","v1.14.1","v1.14.0","v1.13.0","v1.12.1","v1.12.0","v1.11.0","v1.10.1","v1.10.0","v1.9.0","v1.8.2","v1.8.1","v1.8.0","v1.7.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-9595.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}