{"id":"CVE-2026-14631","aliases":["GHSA-m28w-2pqf-7qgj"],"url":"https://o3.security/vulnerability/CVE-2026-14631","summary":"webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header","details":"### Impact\n\nAn unauthenticated peer that can reach the `webpack-dev-server` process can terminate it by sending either a normal HTTP request with a malformed `Host` header, or a WebSocket upgrade to the default `/ws` endpoint with a malformed `Origin` header. The malformed header triggers an uncaught exception in the host-validation path and crashes the dev server process.\n\n### Patches\n\nFixed in `webpack-dev-server` 5.2.6 by treating malformed `Host` and `Origin` header values as invalid rather than throwing (see [PR #5699](https://github.com/webpack/webpack-dev-server/pull/5699)).\n\n### Workarounds\n\nKeep the dev server bound to `localhost` (the default) and do not expose it to untrusted networks.","published":"2026-07-03T17:23:41.451Z","modified":"2026-10-21T02:56:01.988888368Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00517,"percentile":0.42512,"asOf":"2026-09-15"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"webpack-dev-server","fixedVersion":"5.2.6"}],"fix":{"url":"https://github.com/webpack/webpack-dev-server/pull/5699","label":"webpack/webpack-dev-server#5699"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/14xxx/CVE-2026-14631.json"},{"type":"ADVISORY","url":"https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-14631"},{"type":"WEB","url":"https://github.com/webpack/webpack-dev-server/pull/5699"},{"type":"WEB","url":"https://github.com/webpack/webpack-dev-server/commit/f21ed0f44aceb6132abb591ee8b60d770b6e489f"},{"type":"PACKAGE","url":"https://github.com/webpack/webpack-dev-server"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:56:01.988888368Z"}}