HTTP Request Smuggling Affecting io.netty:netty-codec-http package, versions [4.2.0.Final, 4.2.18.Final)[,4.1.138.Final)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-IONETTY-19778369
- published14 Sept 2026
- disclosed10 Sept 2026
- creditdreamlike-ocean, Michael-JRead, August829
Introduced: 10 Sep 2026
NewCVE-2026-89044 (opens in a new tab)How to fix?
Upgrade io.netty:netty-codec-http to version 4.2.18.Final, 4.1.138.Final or higher.
Overview
io.netty:netty-codec-http is a network application framework for rapid development of maintainable high performance protocol servers & clients.
Affected versions of this package are vulnerable to HTTP Request Smuggling due to incomplete validation of request Transfer-Encoding headers. An attacker can inject arbitrary HTTP requests by sending malformed request framing where chunked appears in a Transfer-Encoding field but is not the final transfer-coding token, such as split across multiple header lines or hidden in pseudo-suffix values like chunked, xchunked. The decoder accepts these malformed encodings as chunked and then derives an ambiguous message length, which lets a crafted request be parsed differently by front-end and back-end components. That can desynchronize HTTP processing and allow the attacker to smuggle requests through a proxy or intermediary.