CVE-2026-33871
Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass
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.
How to fix CVE-2026-33871
To remediate CVE-2026-33871, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 4.1.132.Final or later
Is CVE-2026-33871 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- from 0, < 4.1.132.Final
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |