Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced

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Summary

CVECVE-2026-47244
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-12 15:16:29 UTC
Updated2026-06-12 15:55:06 UTC
DescriptionNetty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, DefaultHttp2Connection.DefaultEndpoint initialises maxActiveStreams/maxStreams to Integer.MAX_VALUE, and Http2Settings never inserts SETTINGS_MAX_CONCURRENT_STREAMS by default (Http2Settings.java:305-307 only clamps a user-supplied value). Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), a Netty HTTP/2 server advertises no limit and enforces none locally. Each open stream allocates a DefaultStream object, PropertyMap slots, flow-controller state and IntObjectHashMap entry; with ~2^30 permissible odd stream IDs a single TCP connection can create hundreds of thousands of long-lived stream objects. This is also the precondition for CVE-2023-44487-style Rapid-Reset amplification, where the absence of a low concurrent cap multiplies backend work. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem Types: CWE-400 | CWE-400 CWE-400: Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Netty Netty affected >= 4.2.0.Final, < 4.2.15.Final Not specified
CNA Netty Netty affected < 4.1.135.Final Not specified

References

ReferenceSourceLinkTags
github.com/netty/netty/releases/tag/netty-4.1.135.Final [email protected] github.com
github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q [email protected] github.com
github.com/netty/netty/releases/tag/netty-4.2.15.Final [email protected] github.com
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