# CVE-2026-44892: Netty memory exhaustion in Http3ConnectionHandler

Source: https://junglewise.ai/threats/cve-2026-44892-netty-memory-exhaustion-in-http3connectionhandler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-12. Updated: 2026-06-12  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/io-netty-netty-codec-http3), [Netty Codec HTTP/3](https://junglewise.ai/threats/technologies/codec-http-3). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Netty](https://junglewise.ai/threats/vendors/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

  ```sh
  # 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

- [https://github.com/netty/netty/releases/tag/netty-4.2.15.Final](https://github.com/netty/netty/releases/tag/netty-4.2.15.Final)
- [https://github.com/netty/netty/security/advisories/GHSA-c2rx-5r8w-8xr2](https://github.com/netty/netty/security/advisories/GHSA-c2rx-5r8w-8xr2)

## Related threats

- [Netty memory exhaustion in Http3FrameCodec](https://junglewise.ai/threats/cve-2026-56816-netty-memory-exhaustion-in-http3framecodec)
- [Netty memory exhaustion in HTTP/3 QPACK decoder](https://junglewise.ai/threats/cve-2026-48748-netty-memory-exhaustion-in-http-3-qpack-decoder)
- [Netty unbounded memory allocation in HTTP/3 QPACK decoder](https://junglewise.ai/threats/cve-2026-42582-netty-unbounded-memory-allocation-in-http-3-qpack-decoder)