Vulnerability Details CVE-2026-89044
Netty versions 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final fail to properly validate the final transfer coding in the Transfer-Encoding header, allowing attackers to smuggle requests by using malformed encoding declarations. Attackers can split Transfer-Encoding headers across multiple lines or use values like 'chunked, xchunked' to bypass validation and decode messages as chunked when the final coding is not chunked, enabling request smuggling attacks.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 19.2%
CVSS Severity
CVSS v3 Score 6.5
References
- https://github.com/netty/netty
- https://github.com/netty/netty/blob/netty-4.1.137.Final/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java#L866
- https://github.com/netty/netty/commit/640d4d3324f7b811a4903d0730c8ccb35500500c
- https://github.com/netty/netty/commit/ca87393b0e9e13c493d213a268e727a6d44e1585
- https://github.com/netty/netty/releases/tag/netty-4.1.138.Final
- https://github.com/netty/netty/releases/tag/netty-4.2.18.Final
- https://github.com/netty/netty/security/advisories/GHSA-hcvj-94mj-jp5c
- https://www.vulncheck.com/advisories/netty-4.1.133-final-through-4.1.137-final-and-4.2.13-final-through-4.2.17-final-http-request-smuggling-via-transfer-encoding
Products affected by CVE-2026-89044
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cpe:2.3:a:netty:netty:4.1.133
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cpe:2.3:a:netty:netty:4.1.134
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cpe:2.3:a:netty:netty:4.1.135
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cpe:2.3:a:netty:netty:4.1.136
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cpe:2.3:a:netty:netty:4.1.137
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cpe:2.3:a:netty:netty:4.2.13
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cpe:2.3:a:netty:netty:4.2.14
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cpe:2.3:a:netty:netty:4.2.15
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cpe:2.3:a:netty:netty:4.2.16
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cpe:2.3:a:netty:netty:4.2.17