{"id":"CVE-2026-19484","aliases":["GHSA-xjh9-v7x6-24jw"],"url":"https://o3.security/vulnerability/CVE-2026-19484","summary":"@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary","details":"### Impact\n\nVersions of `@fastify/busboy` from 3.1.0 and prior to 3.2.1 are vulnerable to a Denial of Service. The vendored streaming multipart search stores its default skip distance in a `Uint8Array(256)`. A multipart boundary of exactly 252 bytes makes the search needle 256 bytes, and the table entry wraps to zero, so a crafted request keeps the search in a CPU-bound loop and stalls the Node.js event loop. An unauthenticated client can trigger this with a single small request. Applications that use `@fastify/busboy` to parse multipart/form-data, directly or through `@fastify/multipart`, are affected.\n\n### Patches\n\nFixed in version 3.2.1.\n\n### Workarounds\n\nValidate the multipart boundary before parsing and reject any boundary longer than the RFC 2046 limit of 70 characters (for example at a reverse proxy or in an onRequest hook). Upgrading to 3.2.1 removes the issue.","published":"2026-08-13T08:50:47.361Z","modified":"2026-10-21T02:56:18.722680383Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"@fastify/busboy","fixedVersion":"3.2.1"}],"fix":{"url":"https://github.com/fastify/busboy/commit/632a237e7fb6b3b7a30e0de8fab2ee72ca5bf722","label":"fastify/busboy@632a237"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19484.json"},{"type":"ADVISORY","url":"https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19484"},{"type":"WEB","url":"https://github.com/fastify/busboy/commit/632a237e7fb6b3b7a30e0de8fab2ee72ca5bf722"},{"type":"PACKAGE","url":"https://github.com/fastify/busboy"},{"type":"WEB","url":"https://github.com/fastify/busboy/releases/tag/v3.2.1"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:56:18.722680383Z"}}