CVE-2026-48043: Netty memory exhaustion in DelegatingDecompressorFrameListener

CVE-2026-48043 · Severity: medium · CVSS 5.3 · Published 2026-06-12

Netty is a widely used networking framework that helps developers build high-performance servers and clients. A flaw in how it handles compressed web traffic (HTTP/2) allows a remote attacker to trigger a memory leak. If exploited, this can cause the application to run out of memory and crash, leading to a complete service outage.

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

Quick answers

Is CVE-2026-48043 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-48043 being exploited in the wild.
How severe is CVE-2026-48043?
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=0,fixed=4.1.135.Final; Netty Project Netty Codec HTTP2 <= 4.1.134.Final, >= 4.2.0.Alpha1, <= 4.2.14.Final.
Is there a fix for CVE-2026-48043?
Yes. io.netty:netty-codec-http2 (Maven): upgrade to 4.1.135.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-48043 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-48043?
Check whether you run io.netty:netty-codec-http2 (Maven) 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 4.1.135.Final or later
    # set io.netty:netty-codec-http2 to 4.1.135.Final in your pom.xml or build.gradle

Technical details

A memory leak exists in the `DelegatingDecompressorFrameListener` class within the `netty-codec-http2` module. The component manages HTTP/2 decompression (gzip, deflate, zstd) using an `EmbeddedChannel` where decompressed `ByteBuf` chunks are owned by a tail handler. An attacker can send specifically crafted frames that cause the flow-controller to throw an exception, bypassing the standard release mechanism for these pooled buffers. This results in a reference-count leak that accumulates over time, eventually causing the JVM to crash with an OutOfMemoryError (OOME). The issue is fixed in versions 4.1.135.Final and 4.2.15.Final.

Affected products

  • Netty netty-codec-http2 < 4.1.135.Final, < 4.2.15.Final

Identifiers

  • CVE-2026-48043
  • GHSA-c2gf-v879-257j

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 published to NVD

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.