Answer in brief
CVE-2026-12143 records a High severity (CVSS 7.5) vulnerability in form-data does not escape CR/LF/quote in multipart field names and filenames (CRLF injection). The current sources do not mark it as known exploited. The current feed maps form-data/form-data (generic), form-data (npm), form-data (npm), form-data (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps form-data/form-data (generic), form-data (npm), form-data (npm), form-data (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| form-data/form-datageneric | >=0 <2.5.6 || >=3.0.0 <3.0.5 || >=4.0.0 <4.0.6 | 2.5.6, 3.0.5, 4.0.6 |
| form-datanpm | <2.5.6 | 2.5.6 |
| form-datanpm | >=3.0.0,<3.0.5 | 3.0.5 |
| form-datanpm | >=4.0.0,<4.0.6 | 4.0.6 |
Published upstream
Jun 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 19, 2026
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.
Quoted source text, attributed separately from HOL analysis.