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Critical

HTTP Request Smuggling in Netty

  • Disclosed: 21.02.2020
  • Updated: 11.10.2026 12:21

HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with an incorrect syntax, or might be interpreted as an "invalid fold."

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) io.netty:netty all versions no fix
Java / Kotlin (Maven) io.netty:netty-codec-http < 4.1.44 4.1.44
Java / Kotlin (Maven) org.jboss.netty:netty all versions no fix

References

CVSS score 9.1/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE)
CWE-444
Platform
Java / Kotlin (Maven)
Package
io.netty:netty, io.netty:netty-codec-http, org.jboss.netty:netty
Disclosed
21.02.2020
Updated
11.10.2026 12:21

Sources and licenses

OSV / GitHub Advisory Database - GHSA-cqqj-4p63-rrmm - CC BY 4.0

Vulnerability history: io.netty:netty-codec-http

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 (24) in the archive
Total entries
24
First → latest
02.2020 08.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 1
  • High 6
  • Medium 16
  • Low 1

Disclosures per year

Severity:
  1. Netty: [SpdyHttpDecoder] ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion
    High CVE-2026-56745 >= 4.2.0.Final, < 4.2.16.Final, >= 4.1.0.Final, < 4.1.136.Final 4.2.16.Final, 4.1.136.Final
  2. Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation
    High · 7.5 CVE-2026-55833 >= 4.2.0.Final, < 4.2.16.Final, >= 4.1.0.Final, < 4.1.136.Final 4.2.16.Final, 4.1.136.Final
  3. Netty SPDY SETTINGS frame count materializes unbounded settings map
    High · 7.5 CVE-2026-55831 >= 4.2.0.Final, < 4.2.16.Final, >= 4.1.0.Final, < 4.1.136.Final 4.2.16.Final, 4.1.136.Final
  4. Netty: HttpContentDecompressor maxAllocation bypass when Content-Encoding set to br/zstd/snappy leads to decompression bomb DoS
    High · 7.5 CVE-2026-42587 >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final 4.2.13.Final, 4.1.133.Final
  5. Netty has HttpClientCodec response desynchronization
    High · 7.3 CVE-2026-42584 >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final 4.2.13.Final, 4.1.133.Final
  6. Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing
    High · 7.5 CVE-2026-33870 < 4.1.132.Final, >= 4.2.0.Alpha1, < 4.2.10.Final 4.1.132.Final, 4.2.10.Final
  7. HTTP Request Smuggling in Netty this entry
    Critical · 9.1 CVE-2019-20444 < 4.1.44 4.1.44

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