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CVE-2026-59901 Netty

Affected softwareNetty
Severity8.7 High CVSS 4.0 2 scores
Fixed in4.2.16.Final
WeaknessCWE-835
Published29 Jul 2026
Updated6 Aug 2026

Description

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the Bzip2Decoder handler in Netty's compression codec pipeline is vulnerable to a denial-of-service attack through a malformed bzip2 stream that permanently captures the event-loop thread in an infinite loop. The vulnerability exists in the run-length encoding (RLE) state machine within [Bzip2BlockDecompressor.read()]. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Exploitation status

No public exploit

No exploit has been reported in the sources we check.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: none
  • Indexed PoC none indexed
  • EPSS 0.46% 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.

  • 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/security/advisories/GHSA-558v-64gr-wgg4 : the maintainers' own security advisory: names the version that fixes it, so the fix is the difference between two releases

CVSS

8.7 HIGH v4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 4.0 8.7 HIGH CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X security-advisories@github.com Secondary published
CVSS 3.1 7.5 HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H NVD Primary

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
Oracle Critical Patch Update October 2026 ↗ CPU 2026-Q4 Oracle Communications / Third Party (Netty) (25.1.200, 25.2.100, 25.2.200)
Oracle Retail Applications / Xenvironment (Netty) (22.0.3, 23.0.3, 24.0.2)
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 Third Party (Netty) 25.1.200, 25.2.100, 25.2.200 25.1.200 · 25.2.100 · 25.2.200
Oracle Communications Third Party Patch (Netty) 8.0-8.1
Oracle Retail Applications Xenvironment (Netty) 22.0.3, 23.0.3, 24.0.2 22.0.3 · 23.0.3 · 24.0.2

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
io.netty:netty-codec-compression 4.2.0.Final 4.2.16.Final unbounded
io.netty:netty-codec 0 4.1.136.Final unbounded

Products and versions

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

References

URLTags
https://github.com/netty/netty/security/advisories/GHSA-558v-64gr-wgg4 advisory
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

Published2026-07-29By the CVE Program.
NVD record modified2026-08-06NVD's own last-modified date for this record.