CVE-2026-44892: Netty memory exhaustion in Http3ConnectionHandler

CVE-2026-44892 · Severity: high · CVSS 7.5 · Published 2026-06-12

Netty is a popular framework used by developers to build high-performance network applications and servers. A vulnerability in its HTTP/3 component allows a remote attacker to crash the application by sending an excessive amount of header data. This results in a denial-of-service (DoS) condition, making the affected service unavailable to legitimate users.

Technologies: io.netty:netty-codec-http3 (Maven), Netty Codec HTTP/3. Vendors: Maven, Netty.

Quick answers

Is CVE-2026-44892 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-44892 being exploited in the wild.
How severe is CVE-2026-44892?
High severity, with a CVSS score of 7.5, published 12 June 2026.
Which products and versions are affected?
io.netty:netty-codec-http3 (Maven) >= 4.2.0.Final, <= 4.2.14.Final, ECOSYSTEM:introduced=4.2.0.Final,fixed=4.2.15.Final; Netty Codec HTTP/3 >= 4.2.0.Final, <= 4.2.14.Final.
Is there a fix for CVE-2026-44892?
Yes. io.netty:netty-codec-http3 (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-2026-44892 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-44892?
Check whether you run io.netty:netty-codec-http3 (Maven) or Netty Codec HTTP/3 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-http3 (Maven): upgrade to 4.2.15.Final or later
    # set io.netty:netty-codec-http3 to 4.2.15.Final in your pom.xml or build.gradle

Technical details

The vulnerability exists in the Netty HTTP/3 codec due to an insecure default configuration in the `Http3ConnectionHandler`. When a peer does not explicitly specify `HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE`, the implementation defaults to an unbounded limit, deviating from the secure-by-default 8192-byte limit Netty applies to HTTP/1.1 and HTTP/2. An unauthenticated remote attacker can exploit this by sending an enormous number of headers, leading to an `OutOfMemoryError` and application crash. The issue is rooted in `Http3FrameCodec` where the `maxHeaderListSize` is initialized without a safe upper bound. This is addressed in version 4.2.15.Final by enforcing a default limit.

Affected products

  • Netty netty-codec-http3 >= 4.2.0.Final, <= 4.2.14.Final

Identifiers

  • CVE-2026-44892
  • GHSA-c2rx-5r8w-8xr2

Timeline

  • 2026-06-02: patched: Release of version 4.2.15.Final
  • 2026-06-05: advisory: GitHub Security Advisory GHSA-c2rx-5r8w-8xr2 published
  • 2026-06-12: disclosed: CVE published to NVD

References

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