VulnerabilityAnalyzed

CVE-2026-47244

Netty is a network application framework for development of protocol servers and clients.

MEDIUM 5.3EPSS 0.29%

Does this matter?

Lower severity and a low EPSS score (0.29%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.29% probability · 22th percentile
CISA KEV: Not listed
Weakness: CWE-400
Affected: netty/netty
Source: security-advisories@github.com

References

https://github.com/netty/netty/releases/tag/netty-4.1.135.FinalRelease Notes
https://github.com/netty/netty/releases/tag/netty-4.2.15.FinalRelease Notes
https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6qVendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.