CRLF injection in Netty - CVE-2026-59921

Vulnerability identifier: #VU137576

CSH Severity: Low

CVSS v4: 6.9 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59921

CWE-ID: CWE-93

Exploitation vector: Adjecent network

Exploit availability: No public exploit available

The vulnerability allows a remote user to inject arbitrary MIME headers into multipart request parts.

The vulnerability exists due to improper neutralization of CRLF sequences in io.netty.handler.codec.http.multipart.HttpPostRequestEncoder when constructing multipart HTTP request bodies using user-controlled filenames or field names. A remote user can supply a specially crafted filename or form field name to inject arbitrary MIME headers into multipart request parts.

Exploitation requires application use of the multipart encoder with user-controlled filename or field name data that is forwarded without sanitization.

Netty
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
Development Tools Module
SUSE Package Hub 15
netty-tcnative-debugsource
netty-tcnative
netty
netty-javadoc

Install security update from vendor's website.

Netty - addressed in versions 4.1.136, 4.2.16
netty-tcnative-debugsource - update to 2.0.80-150200.3.48.1
netty-tcnative - update to 2.0.80-150200.3.48.1
netty - update to 4.1.136-150200.4.53.1
netty-javadoc - update to 4.1.136-150200.4.53.1

• https://github.com/netty/netty/security/advisories/GHSA-gcjf-9mgh-3p7g

• Multiple vulnerabilities in Netty
• SUSE update for netty, netty-tcnative