CVE-2026-59921

Severity CVSS v4.0:

Pending analysis

Type:

CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')

Publication date:

28/07/2026

Last modified:

07/08/2026

Description

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&#39; 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.

Impact

Vector 3.x

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.70 MEDIUM
Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector (AV): Adjacent
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): None