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.
Published: 2026-03-27
Score: 8.7 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service (CPU exhaustion)
Action: Apply Patch
AI Analysis

Impact

A remote attacker can send a flood of HTTP/2 CONTINUATION frames that bypass existing size limits by using zero-byte frames, causing the Netty server to consume excessive CPU resources and become unresponsive. This is a resource exhaustion flaw identified as CWE-770.

Affected Systems

Netty versions prior to 4.1.132.Final and 4.2.10.Final are affected.

Risk and Exploitability

The vulnerability has a CVSS score of 8.7, indicating high severity, but the EPSS score is below 1%, suggesting low likelihood of widespread exploitation. It is not listed in the CISA KEV catalog. The attack vector is remote, requiring only network access to an HTTP/2-enabled Netty server, and can be performed with minimal bandwidth.

Generated by OpenCVE AI on March 31, 2026 at 04:23 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Netty to version 4.1.132.Final, 4.2.10.Final, or a later release that contains the fix.
  • If an immediate upgrade is not possible, configure the server or a network device to rate‑limit the number of HTTP/2 CONTINUATION frames allowed from a single client or to reject oversized frames.
  • Verify that no custom configuration re‑enables unrestricted CONTINUATION frame processing after the upgrade.

Generated by OpenCVE AI on March 31, 2026 at 04:23 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-w9fj-cfpg-grvv Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass
History

Tue, 31 Mar 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 31 Mar 2026 03:00:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important

Mon, 30 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Mon, 30 Mar 2026 07:15:00 +0000

Type Values Removed Values Added
First Time appeared Netty
Netty netty
Vendors & Products Netty
Netty netty

Fri, 27 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
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.
Title Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 8.7, 'vector': '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'}

Subscriptions

Netty Netty
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-31T18:54:19.771Z

Reserved: 2026-03-24T15:10:05.679Z

Link: CVE-2026-33871

cve-icon Vulnrichment

Updated: 2026-03-31T18:51:36.828Z

cve-icon NVD

Status : Analyzed

Published: 2026-03-27T20:16:34.833

Modified: 2026-03-30T20:10:17.620

Link: CVE-2026-33871

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-27T19:55:23Z

Links: CVE-2026-33871 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-03-31T20:00:44Z

Weaknesses