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CVE-2026-50020— Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted

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 4.1.135.Final之前版本和4.2.15.Final之前版本存在输入验证错误漏洞，该漏洞源于HttpObjectDecoder在读取第一个请求行前跳过包括NUL字节在内的ISO控制字符，导致请求边界混淆，可能被利用于管道或多路复用传输中的攻击。

CVSS 5.3 · Medium EPSS 0.40% · P32

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
netty netty >= 4.2.0.Final, < 4.2.15.Final affected
< 4.1.135.Final affected
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I. Basic Information for CVE-2026-50020

Vulnerability Information
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Vulnerability Title
Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted
Source: CVE Program / CVE List V5
Vulnerability Description
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
HTTP请求的解释不一致性(HTTP请求私运)
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 4.1.135.Final之前版本和4.2.15.Final之前版本存在输入验证错误漏洞，该漏洞源于HttpObjectDecoder在读取第一个请求行前跳过包括NUL字节在内的ISO控制字符，导致请求边界混淆，可能被利用于管道或多路复用传输中的攻击。
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.Final, < 4.2.15.Final -

II. Public POCs for CVE-2026-50020

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III. Intelligence Information for CVE-2026-50020

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Vendor Advisories for CVE-2026-50020 (1)

Vendor Pages for CVE-2026-50020 (2)

Same Patch Batch · netty · 2026-06-12 · 19 CVEs total

CVE-2026-45674 8.7 HIGH Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records
CVE-2026-47691 8.7 HIGH Netty has Insufficient Bailiwick Validation for NS Records
CVE-2026-48059 8.7 HIGH Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memo
CVE-2026-48006 8.7 HIGH Netty's Lack of Lifecycle Cleanup Leads to Pooled ByteBuf Leak in RedisArrayAggregator
CVE-2026-44892 7.5 HIGH Netty has a Vulnerable Default Configuration Which Leads to Denial of Service via Unbounde
CVE-2026-44894 7.5 HIGH Netty's Default QUIC token handler accepts any client-supplied token
CVE-2026-44893 7.5 HIGH Netty: HAProxy SSL TLV parsing leaks retained slice on invalid TLV length
CVE-2026-46340 7.5 HIGH Netty: SCTP reassembly nests buffers without bound
CVE-2026-50011 7.5 HIGH Netty has unbounded pre-allocation in RedisArrayAggregator from RESP array length
CVE-2026-50010 7.5 HIGH Netty's wrapping plain trust manager silently disables hostname verification
CVE-2026-48748 7.5 HIGH Netty HTTP/3 QPACK Blocked Streams Memory Exhaustion
CVE-2026-45416 7.5 HIGH Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes
CVE-2026-45673 6.8 MEDIUM Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port
CVE-2026-48043 5.3 MEDIUM netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Lea
CVE-2026-47244 5.3 MEDIUM Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced
CVE-2026-50009 4.8 MEDIUM Netty QUIC stateless reset token material exposed through header-visible connection IDs
CVE-2026-45536 4.0 MEDIUM Netty: Unix-socket fd receive leaks descriptors when peer sends two at once
CVE-2026-50560 Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature

IV. Related Vulnerabilities

Same product: netty
Same vendor: netty
Same weakness: CWE-444

V. Comments for CVE-2026-50020

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