Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-59921— Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

Quick assessment

Affected
netty netty
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Netty是Netty团队开源的一款非阻塞I/O客户端-服务器框架,它主要用于开发Java网络应用程序,如协议服务器和客户端等。 Netty 4.1.136.Final之前版本和4.2.16.Final之前版本存在输入验证错误漏洞，该漏洞源于HttpPostRequestEncoder直接将用户提供的文件名和字段名拼接到Content-Disposition MIME头中，未验证或清理CRLF字符，可能导致攻击者注入任意MIME头。

CVSS 5.7 · Medium EPSS 0.46% · P38

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
netty netty >= 4.2.0.Final, < 4.2.16.Final affected
< 4.1.136.Final affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-59921

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder
Source: CVE Program / CVE List V5
Vulnerability 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' 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对CRLF序列的转义处理不恰当(CRLF注入)
Source: CVE Program / CVE List V5
Vulnerability Title
Netty 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Netty是Netty团队开源的一款非阻塞I/O客户端-服务器框架,它主要用于开发Java网络应用程序,如协议服务器和客户端等。 Netty 4.1.136.Final之前版本和4.2.16.Final之前版本存在输入验证错误漏洞，该漏洞源于HttpPostRequestEncoder直接将用户提供的文件名和字段名拼接到Content-Disposition MIME头中，未验证或清理CRLF字符，可能导致攻击者注入任意MIME头。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
netty netty >= 4.2.0.Final, < 4.2.16.Final -

II. Public POCs for CVE-2026-59921

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-59921

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-59921 (1)

Same Patch Batch · netty · 2026-07-28 · 3 CVEs total

CVE-2026-56821 7.4 HIGH Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator
CVE-2026-56822 7.4 HIGH Netty: TOCTOU in OcspServerCertificateValidator

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-93

V. Comments for CVE-2026-59921

No comments yet

Leave a comment