CVE-2026-55851

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the `HAProxyMessageDecoder` in Netty's `codec-haproxy` module performs protocol version detection by reading the 13th byte as a signed Java `byte` and widening it to `int` without masking; a PROXY protocol v2 binary prefix followed by version byte `0xFF` sign-extends to `-1`, collides with the decoder's need-more-data sentinel, and causes `ByteToMessageDecoder` to accumulate inbound bytes in an unbounded `cumulation` buffer until direct memory is exhausted. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

CVSS

No CVSS.

References

Link	Resource
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final
https://github.com/netty/netty/security/advisories/GHSA-q6cq-mhr2-jmr5

Configurations

No configuration.

History

21 Jul 2026, 22:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-21 22:17

Updated : 2026-07-23 15:17

NVD link : CVE-2026-55851

Mitre link : CVE-2026-55851

CVE.ORG link : CVE-2026-55851

JSON object : View

Products Affected

No product.

CWE

CWE-400

Uncontrolled Resource Consumption

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