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 (1)

Core 1
Core References

Scores

CVSS v3 7.5
EPSS 0.0060
EPSS Percentile 44.1%
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