{"cve":"CVE-2026-19481","nvd":{"published":"2026-08-13T09:17:12.573","modified":"2026-09-03T19:16:01.753","status":"Analyzed","description":"@fastify/busboy is a multipart form-data parser. In versions 1.0.0 through 3.2.0, an attacker who can submit multipart form-data can crash the parser by sending a part header whose name is a prototype-inherited property such as __proto__ or constructor. The internal header parser stores headers in a plain JavaScript object and assumes each value is an array, so an inherited property name resolves to a truthy non-array value and triggers a TypeError. In the common pipe integration the failure surfaces as an error event, but in direct write or end usage the exception is thrown synchronously and can terminate the Node.js process, causing an unauthenticated denial of service. The issue is fixed in @fastify/busboy 3.2.1, which creates the header object with a null prototype. Users should upgrade to 3.2.1.","cvss_v4":null,"cvss_v3":{"version":"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},"cwes":["CWE-754"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/busboy/security/advisories/GHSA-x8mw-p69m-v3mx"],"products":["fastify:fastify\\/busyboy"],"source":"nvd","synced_at":"2026-10-19T22:48:17.459049833+00:00"},"epss":{"cve":"CVE-2026-19481","score":0.00493,"percentile":0.42383,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-x8mw-p69m-v3mx","url":"https://osv.dev/vulnerability/GHSA-x8mw-p69m-v3mx","summary":"@fastify/busboy vulnerable to Denial of Service via prototype-named multipart part header","modified":"2026-10-02T23:30:05.651087437Z","packages":[{"ecosystem":"npm","name":"@fastify/busboy","purl":"pkg:npm/%40fastify/busboy","ranges":[">=1.0.0 <3.2.1"],"fixed":["3.2.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}