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form-data: CRLF injection in Content-Disposition headers

CRLF injection vulnerability in form-data library: field names and filenames are not escaped when building Content-Disposition headers, allowing header injectio

16 Jun 2026Read 1 minSeverity: act now

What changed

CRLF injection vulnerability in form-data library: field names and filenames are not escaped when building Content-Disposition headers, allowing header injection and multipart part smuggling.

Who it affects

Applications that pass untrusted input as field names or filenames to FormData#append.

What to do today

Upgrade to version 4.0.6, 3.0.5, or 2.5.6, or validate/reject field names and filenames containing control characters.

The trail
Collected Audited Written Published