CVE-2026-44248— Netty: Resource exhaustion in MqttDecoder
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之前版本存在资源管理错误漏洞，该漏洞源于MQTT 5标头Properties部分在应用消息大小限制前被解析和缓冲，导致CPU和内存资源消耗过高。
Possible ATT&CK Techniques 1 AI
T1496 · Resource HijackingAffected Version Matrix 4
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| io.netty | netty-codec-mqtt | >= 4.2.0.Alpha1, < 4.2.13.Final |
affected |
< 4.1.133.Final |
affected | ||
| 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-2026-44248
Vulnerability Information
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Vulnerability Title
Netty: Resource exhaustion in MqttDecoder
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, the MQTT 5 header Properties section is parsed and buffered before any message size limit is applied. Specifically, in MqttDecoder, the decodeVariableHeader() method is called before the bytesRemainingBeforeVariableHeader > maxBytesInMessage check. The decodeVariableHeader() can call other methods which will call decodeProperties(). Effectively, Netty does not apply any limits to the size of the properties being decoded. Additionally, because MqttDecoder extends ReplayingDecoder, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion. This can cause high resource usage in both CPU and memory. 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:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
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之前版本存在资源管理错误漏洞，该漏洞源于MQTT 5标头Properties部分在应用消息大小限制前被解析和缓冲，导致CPU和内存资源消耗过高。
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 | - |
|
| io.netty | netty-codec-mqtt | >= 4.2.0.Alpha1, < 4.2.13.Final | - |
|
II. Public POCs for CVE-2026-44248
| # | POC Description | Source Link | Shenlong Link |
|---|
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Vendor Advisories for CVE-2026-44248 (1)
-
🔗 MQTT: Resource exhaustion in MqttDecoder · Advisory · netty/netty · GitHub x_refsource_CONFIRM
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-2026-42579 | 7.5 HIGH | Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) |
| 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-2026-42578 | 2.9 LOW | Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation |
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V. Comments for CVE-2026-44248
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