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High

HTTP Request Smuggling in Netty

  • Disclosed: 21.02.2020
  • Updated: 11.10.2026 12:21

Netty 4.1.43.Final allows HTTP Request Smuggling because it mishandles Transfer-Encoding whitespace (such as a [space]Transfer-Encoding:chunked line) and a later Content-Length header. This issue exists because of an incomplete fix for CVE-2019-16869.

Affected software

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PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) io.netty:netty-handler >= 4.1.43, < 4.1.45 4.1.45

References

CVSS score 7.5/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE)
CWE-444
Platform
Java / Kotlin (Maven)
Package
io.netty:netty-handler
Disclosed
21.02.2020
Updated
11.10.2026 12:21

Sources and licenses

OSV / GitHub Advisory Database - GHSA-ff2w-cq2g-wv5f - CC BY 4.0

Vulnerability history: io.netty:netty-handler

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (12) in the archive
Total entries
12
First → latest
02.2020 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 1
  • High 7
  • Medium 4

Disclosures per year

Severity:
  1. Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext
    Critical CVE-2026-75595 >= 4.2.0.Final, < 4.2.17.Final, < 4.1.137.Final 4.2.17.Final, 4.1.137.Final
  2. Netty: Wrapping plain trust manager silently disables hostname verification
    High · 7.5 CVE-2026-50010 >= 4.2.0.Final, < 4.2.15.Final, < 4.1.135.Final 4.2.15.Final, 4.1.135.Final
  3. Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes
    High · 7.5 CVE-2026-45416 >= 4.2.0.Final, < 4.2.15.Final, < 4.1.135.Final 4.2.15.Final, 4.1.135.Final
  4. Netty has an IPv6 Subnet Filter Bypass via Incorrect Comparator Masking
    High · 8.1 CVE-2026-44249 >= 4.2.0.Final, < 4.2.15.Final, < 4.1.135.Final 4.2.15.Final, 4.1.135.Final
  5. SslHandler doesn't correctly validate packets which can lead to native crash when using native SSLEngine
    High · 7.5 CVE-2025-24970 >= 4.1.91.Final, < 4.1.118.Final 4.1.118.Final
  6. Loop with Unreachable Exit Condition in Netty
    High · 7.5 CVE-2016-4970 >= 4.0.0.Alpha1, < 4.0.37.Final, >= 4.1.0.Beta1, < 4.1.1.Final 4.0.37.Final, 4.1.1.Final
  7. Denial of Service in Netty
    High · 7.5 CVE-2020-11612 >= 4.1.0, < 4.1.46 4.1.46
  8. HTTP Request Smuggling in Netty this entry
    High · 7.5 CVE-2020-7238 >= 4.1.43, < 4.1.45 4.1.45

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