CVE-2026-47244: Netty uncontrolled resource consumption in HTTP/2 codec

CVE-2026-47244 · Severity: medium · CVSS 5.3 · Published 2026-06-12

Netty is a widely used networking framework for building Java applications. A vulnerability in its HTTP/2 implementation allows a remote attacker to open an unlimited number of streams on a single connection, consuming excessive server memory and processing power. This can lead to a denial-of-service (DoS) condition, making the application unavailable to legitimate users.

Technologies: io.netty:netty-codec-http2 (Maven), Netty Project Netty Codec HTTP2. Vendors: Maven, Netty Project.

Quick answers

Is CVE-2026-47244 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-47244 being exploited in the wild.
How severe is CVE-2026-47244?
Medium severity, with a CVSS score of 5.3, published 12 June 2026.
Which products and versions are affected?
io.netty:netty-codec-http2 (Maven) ECOSYSTEM:introduced=4.2.0.Final,fixed=4.2.15.Final; Netty Project Netty Codec HTTP2 < 4.1.135.Final, 4.2.0.Final - 4.2.14.Final.
Is there a fix for CVE-2026-47244?
Yes. io.netty:netty-codec-http2 (Maven): upgrade to 4.2.15.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-47244 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-47244?
Check whether you run io.netty:netty-codec-http2 (Maven), Netty Project Codec HTTP/2 or Netty Project Netty Codec HTTP2 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • io.netty:netty-codec-http2 (Maven): upgrade to 4.2.15.Final or later
    # set io.netty:netty-codec-http2 to 4.2.15.Final in your pom.xml or build.gradle

Technical details

The vulnerability exists in the DefaultHttp2Connection component where maxActiveStreams is initialized to Integer.MAX_VALUE by default. Because Http2Settings does not automatically insert a SETTINGS_MAX_CONCURRENT_STREAMS value, a Netty server may advertise and enforce no limit on concurrent streams unless explicitly configured by the developer. An attacker can exploit this by opening hundreds of thousands of long-lived stream objects (DefaultStream, PropertyMap, etc.) over a single TCP connection, leading to uncontrolled memory consumption (CWE-400). This lack of a concurrent cap also facilitates Rapid-Reset style amplification attacks. The issue is resolved in versions 4.1.135.Final and 4.2.15.Final.

Affected products

  • Netty netty-codec-http2 < 4.1.135.Final, 4.2.0.Final - 4.2.14.Final

Identifiers

  • CVE-2026-47244
  • GHSA-5x3r-wrvg-rp6q

Timeline

  • 2026-06-02: patched: Versions 4.1.135.Final and 4.2.15.Final released
  • 2026-06-05: advisory: GitHub Security Advisory published
  • 2026-06-12: disclosed: CVE-2026-47244 published to NVD

References

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