{"id":"GHSA-qq8j-7v2v-3rwp","revision":null,"records":[{"revision":"1cf958cf0f7d49ca9c77bfe45003c02f","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-109855","aliases":[],"title":"undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake","description":"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.","state":0,"publishedAt":"2026-10-15T08:12:51.245+00:00","modifiedAt":"2026-10-15T14:22:28.644+00:00","affected":[{"ecosystem":"Vendor product","name":"undici","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"undici\",\n                    \"product\": \"undici\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"versions\": [\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"affected\",\n                            \"version\": \"8.11.0\",\n                            \"lessThan\": \"8.11.2\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"unaffected\",\n                            \"version\": \"8.11.2\"\n                        }\n                    ],\n                    \"packageURL\": \"pkg:npm/undici\"\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","https://cna.openjsf.org/security-advisories.html"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-109855","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-109855","identifiers":["CVE-2026-109855"]},"retained":false,"historicalAffected":[]},{"revision":"85bf1233e88e46cf8947eb9b05a05024","observedAt":"2026-10-30T01:55:44.649+00:00","statement":{"source":"euvd","id":"EUVD-2026-101959","aliases":["CVE-2026-109855","GHSA-qq8j-7v2v-3rwp"],"title":"undici is an HTTP client library for Node.js. 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As a workaround, set allowH2 to false to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":null}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","https://cna.openjsf.org/security-advisories.html"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-101959","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 15, 2026, 8:12:51 AM","dateUpdated":"Oct 15, 2026, 2:22:28 PM"},"relatedAdvisories":[{"id":"RHSA-2026:76677","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","vulnerabilityIds":["CVE-2024-24786","CVE-2026-56851","CVE-2026-61801","CVE-2026-95502","CVE-2026-97394","CVE-2026-100347","CVE-2026-100348","CVE-2026-100349","CVE-2026-100350","CVE-2026-100351","CVE-2026-101899","CVE-2026-109855"]},{"id":"RHSA-2026:83198","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","vulnerabilityIds":["CVE-2026-109855"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-101959","identifiers":["EUVD-2026-101959","CVE-2026-109855","GHSA-qq8j-7v2v-3rwp"]},"retained":false,"historicalAffected":[]},{"revision":"694f8d38e589499fba12f777e638867b","observedAt":"2026-10-27T16:45:50.731+00:00","statement":{"source":"nvd","id":"CVE-2026-109855","aliases":[],"title":"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 …","description":"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.","state":0,"publishedAt":"2026-10-15T09:17:16.573+00:00","modifiedAt":"2026-10-19T20:46:49.4+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-109855","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-248","CWE-754"],"productCriteria":["cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*"],"sourceDates":{"published":"2026-10-15T09:17:16.573","lastModified":"2026-10-19T20:46:49.400"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-109855","identifiers":["CVE-2026-109855"]},"retained":false,"historicalAffected":[]},{"revision":"d5ae20a622e54ed5b7b7fd90db54a14b","observedAt":"2026-10-27T16:44:03.037+00:00","statement":{"source":"osv","id":"GHSA-qq8j-7v2v-3rwp","aliases":["CVE-2026-109855"],"title":"undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake","description":"### Impact\n\nundici's experimental WebSocket client (enabled by default via `allowH2: true`) crashes the Node.js process when it connects to a malicious server over HTTP/2. If the server answers the WebSocket upgrade with a response that fails handshake validation, undici aborts the request, but the abort is a no-op because the request is already marked completed, so the underlying `ClientHttp2Stream` is left open with no error listener. When the server then destroys the connection, the orphaned stream emits an unhandled `error` and the process exits. A remote, unauthenticated server can therefore deny service to any client that opens a WebSocket to it over HTTP/2. undici 8.11.0 and 8.11.1 are affected; the regression was introduced in 8.11.0.\n\n### Patches\n\nUpgrade to `8.11.2`.\n\n### Workarounds\n\nSet `allowH2: false` to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers, until upgrading.","state":0,"publishedAt":"2026-10-27T16:09:45+00:00","modifiedAt":"2026-10-27T16:15:05.3463355+00:00","affected":[{"ecosystem":"npm","name":"undici","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"8.11.0"},{"kind":"fixed","version":"8.11.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","https://nvd.nist.gov/vuln/detail/CVE-2026-109855","https://github.com/nodejs/undici/pull/5873","https://github.com/nodejs/undici/commit/dd28c5c55f4a25f7c441fd4365b1191f96c3b8bf","https://cna.openjsf.org/security-advisories.html","https://github.com/nodejs/undici","https://github.com/nodejs/undici/releases/tag/v8.11.2"],"sourceUrl":"https://github.com/advisories/GHSA-qq8j-7v2v-3rwp","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-qq8j-7v2v-3rwp","identifiers":["GHSA-qq8j-7v2v-3rwp","CVE-2026-109855"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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