Netty
CVE-2021-43797
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V4 - API and Web Service HTTP request consistency
|
| Impact | CVSS score of 6.5 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required. |
| Exploit ScenarioDerived | A remote attacker could manipulate HTTP request interpretation between frontend and backend servers by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAI
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This HTTP Request/Response Smuggling vulnerability could allow attackers to manipulate HTTP request interpretation between frontend and backend servers.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Enforce strict HTTP parsing, normalize requests at proxy layer, use HTTP/2 end-to-end, reject ambiguous headers.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 3 packages in maven
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444), which allows attackers to manipulate HTTP request interpretation between frontend and backend servers. Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final. Affected products include: Netty, Quarkus, Netapp Oncommand Workflow Automation, Netapp Snapcenter, Oracle Banking Deposits And Lines Of Credit Servicing. Version information: version 4.1.71..
Know when Netty gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
HTTP request smuggling exploits inconsistencies in how front-end and back-end servers parse HTTP message boundaries.
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
Affected Products (CPE)NVD
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour
Netty before 4.1.42.Final mishandles whitespace before the colon in HTTP headers (such as a "Transfer-Encoding : chunked
Certificate revocation-check bypass in the Netty network framework's OCSP client (io.netty:netty-handler-ssl-ocsp) affec
netty-incubator-codec-ohttp is the OHTTP implementation for netty. Rated critical severity (CVSS 9.1), this vulnerabilit
The netty incubator codec.bhttp is a java language binary http parser. Rated high severity (CVSS 8.1), this vulnerabilit
Netty, an asynchronous, event-driven network application framework, has a vulnerability starting in version 4.1.91.Final
Memory exhaustion in Netty's SctpMessageCompletionHandler (netty-transport-sctp) allows unauthenticated remote peers to
Compression-amplification denial of service in the Netty network framework (versions prior to 4.1.136.Final and 4.2.16.F
Memory-amplification denial of service in the Netty network framework (SPDY/3.1 codec) prior to 4.1.136.Final and 4.2.16
Memory-exhaustion denial of service in Netty's HTTP/3 codec (Http3FrameCodec) affects all releases prior to 4.2.16.Final
Netty's HTTP CORS handler silently rewrites the Vary response header to Vary: Origin in releases before 4.1.137.Final an
Denial of service in the Netty HTTP/3 codec (io.netty:netty-codec-http3) prior to version 4.2.15.Final allows remote una
Exploit-DB