CVE-2026-33871

HIGH

Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass

Title source: cna
STIX 2.1

Description

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.

References (20)

Core 20
Core References

Scores

CVSS v3 7.5
EPSS 0.0112
EPSS Percentile 63.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-770
Status published
Products (4)
io.netty/netty-codec-http2 0 - 4.1.132.FinalMaven
netty/netty < 4.1.132
netty/netty < 4.1.132.Final
netty/netty >= 4.2.0.Alpha1, < 4.2.10.Final
Published Mar 27, 2026
Tracked Since Mar 29, 2026