{"schema_version":"1.7.5","id":"GHSA-vxpw-j846-p89q","published":"2026-06-19T14:22:01Z","modified":"2026-06-20T22:59:14.004992698Z","aliases":["CVE-2026-12151"],"related":["CGA-25v4-996r-f3gh"],"summary":"undici WebSocket client vulnerable to denial of service via fragment count bypass","details":"## Impact\n\nThe undici WebSocket client enforces `maxPayloadSize` on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.\n\nAffected applications are those using the undici WebSocket client (`new WebSocket(...)`) or the `WebSocketStream` API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.\n\nAll releases starting at undici 6.17.0 are affected.\n\n## Patches\n\nUpgrade to undici v6.27.0, v7.28.0 or v8.5.0.\n\n## Workarounds\n\nNo workaround is available. The fix must be applied through an upgrade.","affected":[{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"6.27.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-vxpw-j846-p89q/GHSA-vxpw-j846-p89q.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.28.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-vxpw-j846-p89q/GHSA-vxpw-j846-p89q.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0"},{"fixed":"8.5.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-vxpw-j846-p89q/GHSA-vxpw-j846-p89q.json"}}],"references":[{"type":"WEB","url":"https://github.com/nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-12151"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/nodejs/undici"}],"database_specific":{"cwe_ids":["CWE-400","CWE-770"],"github_reviewed":true,"github_reviewed_at":"2026-06-19T14:22:01Z","nvd_published_at":"2026-06-17T17:16:42Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}