# CVE-2026-48043: Netty memory exhaustion in DelegatingDecompressorFrameListener

Source: https://junglewise.ai/threats/cve-2026-48043-netty-memory-exhaustion-in-delegatingdecompressorframelistener  
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-2026-48043 · 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)](https://junglewise.ai/threats/technologies/io-netty-netty-codec-http2), [Netty Project Netty Codec HTTP2](https://junglewise.ai/threats/technologies/netty-codec-http2). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Netty Project](https://junglewise.ai/threats/vendors/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

  ```sh
  # 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

- [https://github.com/netty/netty/releases/tag/netty-4.1.135.Final](https://github.com/netty/netty/releases/tag/netty-4.1.135.Final)
- [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-c2gf-v879-257j](https://github.com/netty/netty/security/advisories/GHSA-c2gf-v879-257j)

## Related threats

- [Netty request smuggling via Host header duplication in HTTP/2 translation](https://junglewise.ai/threats/cve-2026-59900-netty-request-smuggling-via-host-header-duplication-in-http-2)
- [Netty memory leak in HTTP/2 content decompression](https://junglewise.ai/threats/cve-2026-56819-netty-memory-leak-in-http-2-content-decompression)
- [Netty denial of service in HTTP/2 codec via max header size handling](https://junglewise.ai/threats/cve-2026-50560-netty-denial-of-service-in-http-2-codec-via-max-header-size)
- [Netty uncontrolled resource consumption in HTTP/2 codec](https://junglewise.ai/threats/cve-2026-47244-netty-uncontrolled-resource-consumption-in-http-2-codec)
- [Netty denial of service via decompression limit bypass](https://junglewise.ai/threats/cve-2026-42587-netty-denial-of-service-via-decompression-limit-bypass)