{"affected":[{"defaultStatus":"unaffected","ecosystem":"npm","packageName":"@fastify/cors","product":"@fastify/cors","source":"CNA: openjs","vendor":"@fastify/cors","versions":[{"lessThan":"11.4.0","status":"affected","version":"8.2.0","versionType":"semver"},{"status":"unaffected","version":"11.4.0","versionType":"semver"}]}],"cveId":"CVE-2026-120215","cwes":["CWE-248"],"description":"@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.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":3.7,"severity":"low","source":"CNA: openjs","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},{"score":3.7,"severity":"low","source":"NVD: ce714d77-add3-4f53-aff5-83d477b104bb","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}],"modifiedAt":1793618251413,"publishedAt":1793614847667,"references":[{"source":"CNA: openjs","tags":[],"url":"https://github.com/fastify/fastify-cors/security/advisories/GHSA-8c3j-mm64-257c"},{"source":"CNA: openjs","tags":[],"url":"https://cna.openjsf.org/security-advisories.html"},{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":[],"url":"https://cna.openjsf.org/security-advisories.html"},{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":[],"url":"https://github.com/fastify/fastify-cors/security/advisories/GHSA-8c3j-mm64-257c"}],"remediation":[],"revision":"c6de5776abb5c849128204e8b69f82b1f697ceef3e845d67657c34ae8b7c28e8","sources":[{"modifiedAt":1793614847667,"name":"CNA: openjs","retrievedAt":1793617702905,"url":"https://www.cve.org/CVERecord?id=CVE-2026-120215"},{"modifiedAt":1793618251413,"name":"NVD","retrievedAt":1793621823083,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120215"}],"ssvc":null,"status":"published","title":"@fastify/cors vulnerable to Denial of Service on a CORS preflight with the onSend hook","updatedAt":1793621823083}