{"cve":"CVE-2026-12143","nvd":{"published":"2026-06-12T19:16:26.560","modified":"2026-09-11T13:17:04.787","status":"Awaiting Analysis","description":"form-data is a library for creating readable multipart/form-data streams. In versions through 4.0.5, the `field` argument to `FormData#append` and the `filename` option are concatenated verbatim into the `Content-Disposition` header without escaping carriage return (CR), line feed (LF), or double-quote (\") characters. An application that passes attacker-controlled data as a field name or filename (for example, an API gateway that turns JSON object keys into multipart field names) allows the attacker to terminate the header line and inject additional headers, or to smuggle entire additional multipart parts, into the request the application forwards to a backend. This can let the attacker add or override form fields (e.g. set `is_admin=true`) seen by the downstream parser. This is an instance of CWE-93 (CRLF injection). The fix escapes CR, LF, and `\"` as `%0D`, `%0A`, and `%22` in field names and filenames, matching the serialization browsers use per the WHATWG HTML multipart/form-data encoding algorithm. Exploitation requires the consuming application to use untrusted input as a field name or filename; applications that use only fixed/trusted field names are not affected. Fixed in 2.5.6, 3.0.5, and 4.0.6.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","score":8.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":7.5},"cwes":["CWE-93"],"references":["https://cwe.mitre.org/data/definitions/93.html","https://github.com/form-data/form-data/commit/64190db548c0179e37206858e39f27cf513e9435","https://github.com/form-data/form-data/commit/be3f3cf553978bac15a5182f1f3c3d2d38ccf229","https://github.com/form-data/form-data/commit/c7133499c2ee1b80c678e411244f4442bf902045","https://github.com/form-data/form-data/security/advisories/GHSA-hmw2-7cc7-3qxx"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:38:48.522727527+00:00"},"epss":{"cve":"CVE-2026-12143","score":0.00669,"percentile":0.51965,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-hmw2-7cc7-3qxx","url":"https://osv.dev/vulnerability/GHSA-hmw2-7cc7-3qxx","summary":"form-data: CRLF injection in form-data via unescaped multipart field names and filenames","modified":"2026-09-10T03:50:49.785679067Z","packages":[{"ecosystem":"npm","name":"form-data","purl":"pkg:npm/form-data","ranges":["<2.5.6"],"fixed":["2.5.6"]},{"ecosystem":"npm","name":"form-data","purl":"pkg:npm/form-data","ranges":[">=3.0.0 <3.0.5"],"fixed":["3.0.5"]},{"ecosystem":"npm","name":"form-data","purl":"pkg:npm/form-data","ranges":[">=4.0.0 <4.0.6"],"fixed":["4.0.6"]}]}],"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."]}