CVE-2026-12143
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk33th percentile - higher than 33% of all known CVEs
Summary
The form-data library (for creating multipart/form-data streams) before versions 2.5.6, 3.0.5, and 4.0.6 contains a CRLF injection vulnerability. The `field` argument and `filename` option are concatenated verbatim into the Content-Disposition header without escaping CR, LF, or double-quote characters.
Risk Assessment
An attacker can inject additional headers or entire multipart parts, potentially overwriting form fields (e.g., setting is_admin=true) and escalating privileges.
Recommendation
Update the form-data library to version 2.5.6, 3.0.5, or 4.0.6. Ensure that input used as field names is trusted.
Original NVD description (English source)
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.