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CVE-2026-55831 Netty

Affected softwareNetty
Severity7.5 High CVSS 3.1
Fixed in4.2.16.Final, 4.1.136.Final
WeaknessUncontrolled resource consumption (CWE-400)
Published21 Jul 2026
Updated23 Jul 2026

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.

CWE-770

Exploitation status

Proof of concept only

A proof of concept exists, but no reviewed exploit catalogue lists this CVE.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: poc CISA recorded that an exploit has been demonstrated. Automatable: yes, technical impact: partial.
  • Indexed PoC none indexed
  • EPSS 0.66% chance in 30 days

Waratek protection

No exploit published

Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.

A public code fix exists: netty/netty 5b68c61.

  • Protection none
  • Action unverified
  • Review automated Upstream data
  • Record active
Decided by Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all
Finding This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious.
Candidate fix https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b : a commit: the change itself

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
Oracle Critical Patch Update October 2026 ↗ CPU 2026-Q4 Oracle Communications / Signaling (Netty) (25.2.200, 26.1.200)
Oracle Critical Security Patch Update September 2026 ↗ CSPU 2026-Q3 Oracle Communications / Third Party Patch (Netty) (8.0-8.1)

Oracle components and versions

FamilyComponentVersions, as Oracle lists themRead as
Oracle Communications Signaling (Netty) 25.2.200, 26.1.200 25.2.200 · 26.1.200
Oracle Communications Third Party Patch (Netty) 8.0-8.1

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
io.netty:netty-codec-http 4.2.0.Final 4.2.16.Final unbounded
io.netty:netty-codec-http 4.1.0.Final 4.1.136.Final unbounded

Products and versions

2 products, 4 version entries
SourceVendorProductSchemeAffected versions
osv io.netty netty-codec-http generic ≥ 4.1.0 and < 4.1.136 · ≥ 4.2.0 and < 4.2.16
nvd netty netty generic ≥ 4.1.0 and < 4.1.136 · ≥ 4.2.0 and < 4.2.16

References

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

Timeline

Published2026-07-21By the CVE Program.
NVD record modified2026-07-23NVD's own last-modified date for this record.