CVE-2026-55831

HIGH 7.5

Netty SPDY SETTINGS frame count materializes unbounded settings map

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

CWE	CWE-770 CWE-400
Vendor	netty
Product	netty
Published	Jul 20, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

netty / netty

>= 4.2.0.Final, < 4.2.16.Final >= 4.1.0.Final, < 4.1.136.Final

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w github.com: https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b github.com: https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6 github.com: https://github.com/netty/netty/releases/tag/netty-4.1.136.Final github.com: https://github.com/netty/netty/releases/tag/netty-4.2.16.Final