CVE-2026-59921
Published:July 28, 2026
Updated:August 04, 2026
Netty 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.
Affected Packages
io.netty:netty-codec-http (JAVA):
Affected version(s) >=4.0.0.Alpha1 <4.1.136.FinalFix Suggestion:
Update to version 4.1.136.Finalio.netty:netty-codec-http (JAVA):
Affected version(s) >=4.2.0.Final <4.2.16.FinalFix Suggestion:
Update to version 4.2.16.FinalRelated Resources (6)
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Contact UsCVSS v4
Base Score:
6.9
Attack Vector
ADJACENT
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.7
Attack Vector
ADJACENT
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Neutralization of CRLF Sequences ('CRLF Injection')
EPSS
Base Score:
0.28