CVE-2026-33871
March 27, 2026
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.
Affected Packages
io.netty:netty-codec-http2 (JAVA):
Affected version(s) >=4.1.0.Beta4 <4.1.132.FinalFix Suggestion:
Update to version 4.1.132.Finalio.netty:netty-codec-http2 (JAVA):
Affected version(s) >=4.2.0.Alpha1 <4.2.11.FinalFix Suggestion:
Update to version 4.2.11.Finalio.netty:netty-codec-http2 (JAVA):
Affected version(s) >=4.2.0.Alpha1 <4.2.11.FinalFix Suggestion:
Update to version 4.2.11.Finalio.netty:netty-codec-http2 (JAVA):
Affected version(s) >=4.1.0.Beta4 <4.1.132.FinalFix Suggestion:
Update to version 4.1.132.FinalRelated Resources (3)
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Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
