{"id":"CVE-2026-6402","aliases":["GHSA-79cf-xcqc-c78w"],"url":"https://o3.security/vulnerability/CVE-2026-6402","summary":"webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins","details":"webpack-dev-server versions up to and including 5.2.3 are vulnerable to cross-origin source code exposure when serving over a non-potentially trustworthy origin such as plain HTTP. The previous fix relied on the Sec-Fetch-Mode and Sec-Fetch-Site request headers, which browsers omit for non-trustworthy origins, allowing a malicious site to load the bundled source as a script and read it across origins. Impact: an attacker controlling a website visited by a developer running webpack-dev-server can recover the application source code when the dev server runs over HTTP at a guessable host and port. Chromium based browsers from Chrome 142 onward are not affected due to local network access restrictions. Upgrade to webpack-dev-server 5.2.4 or later, which sets Cross-Origin-Resource-Policy: same-origin on responses.","published":"2026-05-12T07:45:21.253Z","modified":"2026-08-12T03:51:10.243517714Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N"},"epss":{"score":0.00216,"percentile":0.12178,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"webpack-dev-server","fixedVersion":"5.2.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6402.json"},{"type":"ADVISORY","url":"https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6402"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:10.243517714Z"}}