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CVE-2026-45416— Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes

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之前版本存在资源管理错误漏洞，该漏洞源于SslClientHelloHandler.decode()方法读取24位TLS握手长度时，当ClientHello不匹配第一个记录时，急切进行大块内存分配且未设置超时，可能导致资源耗尽。以下版本受到影响：4.1.135.Final之前版本和4.2.15.Final

CVSS 7.5 · High EPSS 0.92% · P60

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

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-2026-45416

Vulnerability Information
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Vulnerability Title
Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes
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, SslClientHelloHandler.decode() reads the 24-bit TLS handshake length and, when the ClientHello does not fit in the first record, eagerly allocates `ctx.alloc().buffer(handshakeLength)` (line 161). The guard at line 140 is `handshakeLength > maxClientHelloLength && maxClientHelloLength != 0`, and the commonly-used SniHandler/AbstractSniHandler constructors (SniHandler(Mapping), SniHandler(AsyncMapping), AbstractSniHandler()) pass maxClientHelloLength=0 and handshakeTimeoutMillis=0, so the length guard is disabled and no timeout is scheduled. A 16 MiB request exceeds the default pooled chunk size and becomes a huge/unpooled allocation performed immediately. The buffer is retained in the handler until the channel closes. 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:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
Netty 资源管理错误漏洞
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之前版本存在资源管理错误漏洞，该漏洞源于SslClientHelloHandler.decode()方法读取24位TLS握手长度时，当ClientHello不匹配第一个记录时，急切进行大块内存分配且未设置超时，可能导致资源耗尽。以下版本受到影响：4.1.135.Final之前版本和4.2.15.Final
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-2026-45416

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 11685 chars
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III. Intelligence Information for CVE-2026-45416

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Vendor Advisories for CVE-2026-45416 (1)

Vendor Pages for CVE-2026-45416 (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-2026-45673 6.8 MEDIUM Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port
CVE-2026-50020 5.3 MEDIUM Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRL
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-770