Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced_CVE-2026-47244

5.3 / 10

MEDIUM

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

Description

Netty 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.

Basic Information

ID CVE-2026-47244

Source GitHub_M

Published Jun 12, 2026 at 14:23

Modified Jun 12, 2026 at 14:59

Affected Product

Vendor netty

Product netty

Version >= 4.2.0.Final, < 4.2.15.Final

Affected Versions netty netty >= 4.2.0.Final, < 4.2.15.Final
netty netty < 4.1.135.Final

CWE Classification

CWE-400

References

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    "published": "2026-06-12T14:23:50.316Z",
    "modified": "2026-06-12T14:59:15.823Z",
    "type": "cve",
    "title": "Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced",
    "source": "GitHub_M",
    "references": "https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q\nhttps://github.com/netty/netty/releases/tag/netty-4.1.135.Final\nhttps://github.com/netty/netty/releases/tag/netty-4.2.15.Final",
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