{"id":"CVE-2026-74866","aliases":["GHSA-gxm5-99cw-xjw9"],"url":"https://o3.security/vulnerability/CVE-2026-74866","summary":"@fastify/busboy vulnerable to CRLF injection via multipart Content-Disposition filename and name","details":"### Impact\n\n`@fastify/busboy` 3.2.1 and earlier retains a bare carriage return or line feed inside the parsed `Content-Disposition` parameters returned to the application. The multipart header parser ends a header line only on the two-byte `\\r\\n` sequence, so a lone CR or LF embedded in a part header is carried verbatim into the `filename` and field `name` delivered by the `file` and `field` events. An application that forwards the supplied filename or name into a CR/LF-sensitive sink cannot anticipate the embedded control character.\n\nAn attacker who uploads a file whose `filename` or field `name` contains a bare CR or LF can pollute filenames on disk when the upload is saved under its original name, inject forged lines into logs, or inject headers on a downstream hop that does not re-validate CR/LF, such as object-storage metadata or a proxied backend. Applications using `@fastify/busboy` directly, or through `@fastify/multipart` and its consumers, are affected.\n\n### Patches\n\nUpgrade to `@fastify/busboy` 3.2.2 or later.\n\n### Workarounds\n\nValidate or strip carriage return and line feed characters from the `filename` and field `name` before using them in any filesystem, logging, or outbound-header context.","published":"2026-08-21T08:20:32.672Z","modified":"2026-10-21T02:59:18.314075344Z","cvss":{"score":5.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"@fastify/busboy","fixedVersion":"3.2.2"}],"fix":{"url":"https://github.com/fastify/busboy/commit/cc7da17c5c88d79c314a9e149a79e5a00a6c23be","label":"fastify/busboy@cc7da17"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74866.json"},{"type":"ADVISORY","url":"https://github.com/fastify/busboy/security/advisories/GHSA-gxm5-99cw-xjw9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74866"},{"type":"WEB","url":"https://github.com/fastify/busboy/commit/cc7da17c5c88d79c314a9e149a79e5a00a6c23be"},{"type":"PACKAGE","url":"https://github.com/fastify/busboy"},{"type":"WEB","url":"https://github.com/fastify/busboy/releases/tag/v3.2.2"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:59:18.314075344Z"}}