CVE-2026-33871

Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass

HIGH
7.5
CVSS Score
Published: March 27, 2026 at 07:55 PM UTC
Updated: September 14, 2026 at 01:18 PM UTC
19 products affected across 2 vendorsNettyJBoss Enterprise Application PlatformSingle Sign on

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.1.132v < 4.1.132.Finalv < 4.2.10.Final4.2.0 ≤ v < 4.2.10
Affected range stops below 4.1.132, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.1.132.Final, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.10.Final, so it looks safe — our inference, not a vendor statement
All versions
All versions
Vendor states this is fixed in 3.27.3 (unaffected)
Vendor states this is fixed in codec-http2 (unaffected)
60%
Vendor states this is fixed in 4.2.0-9 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (21)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvv
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:10175
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:10184
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:13571
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:14272
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:14276
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:17668
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:17789

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHredhat-SADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-770

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