High 7.5Published Jul 20, 2026

CVE-2026-55831Netty SPDY SETTINGS frame count materializes unbounded settings map

Updated under an hour ago (Oct 27, 2026, 1:50 AM ET)

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Exploited in the last 30 days

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: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-770, CWE-400
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Jul 23, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty (from the name)	from 4.2.0.Final, < 4.2.16.Final; from 4.1.0.Final, < 4.1.136.Final	CNA record
netty netty netty:netty	from 4.1.0 before 4.1.136; from 4.2.0 before 4.2.16	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w	x-refsource-confirm, exploit, vendor-advisory
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b	x-refsource-misc, patch
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6	x-refsource-misc, patch
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final	x-refsource-misc, release-notes
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.