{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-120215", "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb", "state": "PUBLISHED", "assignerShortName": "openjs", "dateReserved": "2026-10-31T15:01:18.624Z", "datePublished": "2026-11-02T10:20:47.667Z", "dateUpdated": "2026-11-02T10:20:47.667Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "ce714d77-add3-4f53-aff5-83d477b104bb", "shortName": "openjs", "dateUpdated": "2026-11-02T10:20:47.667Z"}, "descriptions": [{"lang": "en", "value": "@fastify/cors is the CORS plugin for the Fastify web framework. In versions 8.2.0 through 11.3.x, an application that registers the plugin with the non-default onSend hook option crashes on a CORS preflight. On an OPTIONS request that carries the Origin and Access-Control-Request-Method headers, the plugin calls reply.send from inside the onSend hook and re-enters the send pipeline, so a second write of the response headers throws an uncaught ERR_HTTP_HEADERS_SENT that can terminate the Node.js process when no process-level handler is installed. An unauthenticated remote client can trigger this with a single preflight request, so the impact is availability only, and exploitation requires the non-default onSend configuration. The issue is fixed in @fastify/cors 11.4.0, where onSend is no longer an accepted hook value and registration fails with a clear error instead of crashing at request time, and users should upgrade to 11.4.0 or later. As a workaround, use any other hook such as the default onRequest, or set preflight to false.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "@fastify/cors is the CORS plugin for the Fastify web framework. In versions 8.2.0 through 11.3.x, an application that registers the plugin with the non-default onSend hook option crashes on a CORS preflight. On an OPTIONS request that carries the Origin and Access-Control-Request-Method headers, the plugin calls reply.send from inside the onSend hook and re-enters the send pipeline, so a second write of the response headers throws an uncaught ERR_HTTP_HEADERS_SENT that can terminate the Node.js process when no process-level handler is installed. An unauthenticated remote client can trigger this with a single preflight request, so the impact is availability only, and exploitation requires the non-default onSend configuration. The issue is fixed in @fastify/cors 11.4.0, where onSend is no longer an accepted hook value and registration fails with a clear error instead of crashing at request time, and users should upgrade to 11.4.0 or later. As a workaround, use any other hook such as the default onRequest, or set preflight to false."}]}], "affected": [{"vendor": "@fastify/cors", "product": "@fastify/cors", "defaultStatus": "unaffected", "versions": [{"versionType": "semver", "status": "affected", "version": "8.2.0", "lessThan": "11.4.0"}, {"versionType": "semver", "status": "unaffected", "version": "11.4.0"}], "packageURL": "pkg:npm/@fastify/cors"}], "references": [{"url": "https://github.com/fastify/fastify-cors/security/advisories/GHSA-8c3j-mm64-257c"}, {"url": "https://cna.openjsf.org/security-advisories.html"}], "credits": [{"lang": "en", "type": "reporter", "value": "Ravin06"}, {"lang": "en", "type": "remediation developer", "value": "mcollina"}, {"lang": "en", "type": "remediation reviewer", "value": "UlisesGascon"}], "title": "@fastify/cors vulnerable to Denial of Service on a CORS preflight with the onSend hook", "metrics": [{"format": "CVSS", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 3.7, "baseSeverity": "LOW"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-248", "lang": "en", "description": "CWE-248: Uncaught Exception", "type": "CWE"}]}], "x_generator": {"engine": "cve-kit 1.0.0"}}}}

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