Netty HTTP/1.1 Chunked Request Smuggling (<4.1.132, <4.2.10)
CVE-2026-33870 Published on March 27, 2026
Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing
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.
Vulnerability Analysis
CVE-2026-33870 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity, and no impact on availability.
Weakness Type
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-33870 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Products Associated with CVE-2026-33870
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Affected Versions
netty:- Version < 4.1.132.Final is affected.
- Version >= 4.2.0.Alpha1, < 4.2.10.Final is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.