Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-59921
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-28 23:17:09 UTC
Updated2026-07-29 18:16:56 UTC
DescriptionNetty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, HttpPostRequestEncoder constructs multipart HTTP request bodies by directly concatenating user-supplied filenames and field names into Content-Disposition MIME headers without validating or sanitizing CRLF characters (\r\n). Since MIME headers are delimited by CRLF, an attacker who controls the filename can inject arbitrary MIME headers into the multipart body part. The root cause is that neither the encoder nor the FileUpload implementations' setFilename() methods, which only check for null, neutralize CRLF characters before the filename is embedded into the header. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Risk And Classification

Primary CVSS: v3.1 5.7 MEDIUM from [email protected]

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

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.7MEDIUMCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED5.7MEDIUMCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Netty Netty affected >= 4.2.0.Final, < 4.2.16.Final Not specified
CNA Netty Netty affected < 4.1.136.Final Not specified

References

ReferenceSourceLinkTags
github.com/netty/netty/security/advisories/GHSA-gcjf-9mgh-3p7g 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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