{"id":"UBUNTU-CVE-2026-109855","details":"undici is an HTTP client library for Node.js. In versions 8.11.0 and 8.11.1, its experimental WebSocket client, which is enabled by default when HTTP/2 is allowed, mishandles a failed WebSocket handshake over HTTP/2: the request is already marked completed, so the abort becomes a no-op and the underlying HTTP/2 stream is left open with no error listener. When a malicious server then destroys the connection, the orphaned stream emits an unhandled error and the Node.js process exits. A remote, unauthenticated server can therefore crash any client that opens a WebSocket to it over HTTP/2, resulting in a denial of service. The issue is fixed in undici 8.11.2, and users should upgrade to 8.11.2 or later. As a workaround, set allowH2 to false to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers.","modified":"2026-10-17T12:58:03.355443909Z","published":"2026-10-15T00:00:00Z","upstream":["CVE-2026-109855"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-109855"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-109855"},{"type":"REPORT","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"REPORT","url":"https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp"}],"affected":[{"package":{"name":"node-undici","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/node-undici?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.22.1+dfsg1+~cs20.10.10.2-1ubuntu1","5.26.3+dfsg1+~cs23.10.12-2"],"ecosystem_specific":{"binaries":[{"binary_name":"node-llhttp","binary_version":"9.1.3~5.26.3+dfsg1+~cs23.10.12-2"},{"binary_version":"5.26.3+dfsg1+~cs23.10.12-2","binary_name":"node-undici"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109855.json"}},{"package":{"name":"node-undici","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/node-undici?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.18.2+dfsg+~cs3.2.0-1build1","7.24.6+dfsg+~cs3.2.0-3","8.5.0+dfsg+~cs3.2.0-2","8.5.0+dfsg+~cs3.2.0-3","8.9.0+dfsg+~cs3.2.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-undici","binary_version":"8.9.0+dfsg+~cs3.2.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109855.json"}},{"package":{"name":"node-undici","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/node-undici?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.3.0+dfsg1+~cs24.12.11-2","7.16.0+dfsg+~cs3.2.0-2","7.18.2+dfsg+~cs3.2.0-1","7.18.2+dfsg+~cs3.2.0-1build1"],"ecosystem_specific":{"binaries":[{"binary_version":"7.18.2+dfsg+~cs3.2.0-1build1","binary_name":"node-undici"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109855.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}