CVE-2026-33871 — Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass

Description (CNA)

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

Affected (CNA)

Vendor / product	Versions
netty / netty	affected < 4.1.132.Final; affected >= 4.2.0.Alpha1, < 4.2.10.Final

CWE

CWE-770

References

https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvv

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in Netty. A remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of CONTINUATION frames. The server's lack of a limit on these frames, coupled with a bypass of size-based mitigations using zero-byte frames, allows an attacker to consume excessive CPU resources. This can render the server unresponsive with minimal bandwidth usage.