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CVE-2026-50020 Netty

Affected softwareNetty
Severity5.3 Medium CVSS 3.1
Fixed in4.2.15.Final, 4.1.135.Final
WeaknessCWE-444
Published12 Jun 2026
Updated17 Jun 2026

Description

Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, HttpObjectDecoder skips every byte for which Character.isISOControl(b) is true (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

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 0.23% 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-hvcg-qmg6-jm4c : the maintainers' own security advisory: names the version that fixes it, so the fix is the difference between two releases

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
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 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 4.2.15.Final unbounded
io.netty:netty-codec-http 0 4.1.135.Final unbounded

Products and versions

2 products, 4 version entries
SourceVendorProductSchemeAffected versions
osv io.netty netty-codec-http generic ＜ 4.1.135 · ≥ 4.2.0 and ＜ 4.2.15
nvd netty netty generic ＜ 4.1.135 · ≥ 4.2.0 and ＜ 4.2.15

References

URLTags
https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c advisory
https://github.com/netty/netty PACKAGE
https://github.com/netty/netty/releases/tag/netty-4.1.135.Final WEB
https://github.com/netty/netty/releases/tag/netty-4.2.15.Final WEB

Timeline
Published2026-06-12By the CVE Program.
NVD record modified2026-06-17NVD's own last-modified date for this record.