netty netty CVE-2021-21409 vulnerability in Netty and Other Products
Published on March 30, 2021

Possible request smuggling in HTTP/2 due missing validation of content-length

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Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.61.Final there is a vulnerability that enables request smuggling. The content-length header is not correctly validated if the request only uses a single Http2HeaderFrame with the endStream set to to true. This could lead to request smuggling if the request is proxied to a remote peer and translated to HTTP/1.1. This is a followup of GHSA-wm47-8v5p-wjpj/CVE-2021-21295 which did miss to fix this one case. This was fixed as part of 4.1.61.Final.

Github Repository Vendor Advisory NVD

Vulnerability Analysis

CVE-2021-21409 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. 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.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
HIGH
Availability Impact:
NONE

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-2021-21409 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2021-21409

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Affected Versions

netty Version < 4.1.61.Final is affected by CVE-2021-21409

Vulnerable Packages

The following package name and versions may be associated with CVE-2021-21409

Package Manager Vulnerable Package Versions Fixed In
maven io.netty:netty-codec-http2 < 4.1.61 4.1.61

Exploit Probability

EPSS
3.16%
Percentile
86.66%

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.