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CVE-2026-42579— Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)

Quick assessment

Affected
netty netty
Exploitation
Public or AI PoC available; prioritize validation
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社区的一款非阻塞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 4.2.13.Final之前版本和4.1.133.Final之前版本存在输入验证错误漏洞，该漏洞源于DNS编解码器未执行RFC 1035域名约束，可能导致双向攻击。

CVSS 7.5 · High EPSS 0.85% · P56

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
netty netty >= 4.2.0.Alpha1, < 4.2.13.Final affected
< 4.1.133.Final affected
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I. Basic Information for CVE-2026-42579

Vulnerability Information
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Vulnerability Title
Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)
Source: CVE Program / CVE List V5
Vulnerability Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's DNS codec does not enforce RFC 1035 domain name constraints during either encoding or decoding. This creates a bidirectional attack surface: malicious DNS responses can exploit the decoder, and user-influenced hostnames can exploit the encoder. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
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社区的一款非阻塞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 4.2.13.Final之前版本和4.1.133.Final之前版本存在输入验证错误漏洞，该漏洞源于DNS编解码器未执行RFC 1035域名约束，可能导致双向攻击。
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.Alpha1, < 4.2.13.Final -

II. Public POCs for CVE-2026-42579

# POC Description Source Link Shenlong Link
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Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
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claude_code · 5330 chars
GitHub 复现环境（可 clone 直接跑）
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III. Intelligence Information for CVE-2026-42579

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Vendor Advisories for CVE-2026-42579 (1)

Same Patch Batch · netty · 2026-05-13 · 12 CVEs total

CVE-2026-42587 7.5 HIGH Netty: HttpContentDecompressor maxAllocation bypass via Content-Encoding: br/zstd/snappy e
CVE-2026-42582 7.5 HIGH Netty: HTTP/3 QPACK literal unbounded allocation
CVE-2026-42583 7.5 HIGH Netty: Lz4FrameDecoder resource exhaustion
CVE-2026-42577 7.5 HIGH Netty: epoll transport denial of service via RST on half-closed TCP connection
CVE-2026-42584 7.3 HIGH Netty: HttpClientCodec response desynchronization
CVE-2026-42586 6.8 MEDIUM Netty: CRLF Injection in Netty Redis Codec Encoder
CVE-2026-42580 6.5 MEDIUM Netty: HTTP Request Smuggling due to incorrect chunk size parsing
CVE-2026-42585 6.5 MEDIUM Netty: HTTP Request Smuggling due to malformed Transfer-Encoding
CVE-2026-42581 5.8 MEDIUM Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization
CVE-2026-44248 5.3 MEDIUM Netty: Resource exhaustion in MqttDecoder
CVE-2026-42578 2.9 LOW Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-20

V. Comments for CVE-2026-42579

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