CVE-2021-21295
5.9 · MEDIUMOverview
CVE-2021-21295 is a medium-severity vulnerability affecting netty netty. It was published on March 9, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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 4.1.60.Final there is a vulnerability that enables request smuggling. If a Content-Length header is present in the original HTTP/2 request, the field is not validated by `Http2MultiplexHandler` as it is propagated up. This is fine as long as the request is not proxied through as HTTP/1.1. If the request comes in as an HTTP/2 stream, gets converted into the HTTP/1.1 domain objects (`HttpRequest`, `HttpContent`, etc.) via `Http2StreamFrameToHttpObjectCodec `and then sent up to the child channel's pipeline and proxied through a remote peer as HTTP/1.1 this may result in request smuggling. In a proxy case, users may assume the content-length is validated somehow, which is not the case. If the request is forwarded to a backend channel that is a HTTP/1.1 connection, the Content-
Remediation
Check the references section for vendor advisories and patches from netty. Update netty to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| netty | netty | >= 0, < 4.1.60 | Affected |
| quarkus | quarkus | 0 | Affected |
| apache | kudu | >= 0, < 1.16.0 | Affected |
References
Frequently Asked Questions
What is CVE-2021-21295?
CVE-2021-21295 is a medium-severity vulnerability affecting netty netty. It was published on March 9, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
How severe is CVE-2021-21295?
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-21295?
Check the references section for vendor advisories and patches from netty. Update netty to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-21295?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-21295 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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