form-data does not escape CR/LF/quote in multipart field names and filenames (CRLF injection)

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Summary

CVECVE-2026-12143
StatePUBLISHED
Assignerharborist
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-12 19:16:26 UTC
Updated2026-06-16 15:42:57 UTC
Descriptionform-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.

Risk And Classification

Primary CVSS: v4.0 8.7 HIGH from 7ffcee3d-2c14-4c3e-b844-86c6a321a158

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.003250000 probability, percentile 0.240750000 (date 2026-06-23)

Problem Types: CWE-93 | CWE-93 CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

VersionSourceTypeScoreSeverityVector
4.07ffcee3d-2c14-4c3e-b844-86c6a321a158Secondary8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
3.17ffcee3d-2c14-4c3e-b844-86c6a321a158Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
High
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Form-data Form-data affected 2.5.6 semver Not specified
CNA Form-data Form-data affected 3.0.0 3.0.5 semver Not specified
CNA Form-data Form-data affected 4.0.0 4.0.6 semver Not specified

References

ReferenceSourceLinkTags
github.com/form-data/form-data/security/advisories/GHSA-hmw2-7cc7-3qxx 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/form-data/form-data/commit/be3f3cf553978bac15a5182f1f3c3d2d38... 7ffcee3d-2c14-4c3e-b844-86c6a321a158 github.com
cwe.mitre.org/data/definitions/93.html 7ffcee3d-2c14-4c3e-b844-86c6a321a158 cwe.mitre.org
github.com/form-data/form-data/commit/c7133499c2ee1b80c678e411244f4442bf... 7ffcee3d-2c14-4c3e-b844-86c6a321a158 github.com
github.com/form-data/form-data/commit/64190db548c0179e37206858e39f27cf51... 7ffcee3d-2c14-4c3e-b844-86c6a321a158 github.com
www.npmjs.com/package/form-data 7ffcee3d-2c14-4c3e-b844-86c6a321a158 www.npmjs.com
html.spec.whatwg.org/multipage/form-control-infrastructure.html 7ffcee3d-2c14-4c3e-b844-86c6a321a158 html.spec.whatwg.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: yueyueL (https://github.com/yueyueL) (en)

CNA: LJHarb (https://github.com/LJHarb) (en)

CNA: LJHarb (https://github.com/LJHarb) (en)

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