CVE-2026-33871
HIGHNetty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass
Title source: cnaDescription
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
X_Refsource_Confirm x_refsource_confirm
https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvv
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