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Vulnerability record · CVE-2026-55831 · published 21 July 2026

CVE-2026-55831: Netty uncontrolled resource consumption vulnerability

Netty · Netty

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.

7.5 CVSS 3.1 High EPSS 0.66% · top 50.2% CWE-400 · Uncontrolled resource consumptionCWE-770 · Allocation without limits
7.5CVSS 3.1 base score
0.66%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
23 Jul 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-55831), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.