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Vulnerability · Published Mar 27, 2026 · Assigned by GitHub_M

CVE-2026-33870Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing

High 7.5

In plain English

A high-severity security flaw in netty from netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.7%top 46.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nettyno fix listedDEBIAN-CVE-2026-33870
Debian:13nettyno fix listedDEBIAN-CVE-2026-33870
Debian:14nettyno fix listedDEBIAN-CVE-2026-33870
Mavenio.netty:netty-codec-http4.2.10.FinalGHSA-pwqr-wmgm-9rr8
Mavenio.netty:netty-codec-http4.1.132.FinalGHSA-pwqr-wmgm-9rr8
Ubuntu:25.10nettyno fix listedUBUNTU-CVE-2026-33870
Ubuntu:26.10nettyno fix listedUBUNTU-CVE-2026-33870

Affected products (as reported)

VendorProductVersions
netty netty < 4.1.132.Final>= 4.2.0.Alpha1, < 4.2.10.Final

Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References