# CVE-2026-93564: Netty reference-count leak in HAProxy PROXY-v2 decoder

Source: https://junglewise.ai/threats/cve-2026-93564-netty-reference-count-leak-in-haproxy-proxy-v2-decoder  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-93564 · Severity: high · CVSS 7.5 · Published 2026-09-18

Netty is a widely used Java networking library that powers many high-performance applications and services. A memory leak flaw in its HAProxy protocol handler allows an attacker to exhaust available memory by sending malformed protocol messages, causing the affected application to crash or become unresponsive. This denial-of-service attack requires no authentication and can be triggered remotely.

Technologies: [Netty](https://junglewise.ai/threats/technologies/netty). Vendors: [Netty](https://junglewise.ai/threats/vendors/netty).

## Quick answers

**Is CVE-2026-93564 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93564 being exploited in the wild.

**How severe is CVE-2026-93564?** High severity, with a CVSS score of 7.5, published 18 September 2026.

**Which products and versions are affected?** Netty Netty.

**Is there a fix for CVE-2026-93564?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-93564 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-93564?** Check whether you run Netty. 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.

## Technical details

The vulnerability is a reference-count leak in Netty's HAProxy PROXY-v2 message decoder. When specially crafted PROXY-protocol v2 headers are received, the decoder fails to properly release memory references, causing them to accumulate over time. An unauthenticated attacker on the network can repeatedly send malformed PROXY-v2 messages to trigger this leak, leading to memory exhaustion and eventual denial of service. The attack is network-accessible and requires no prior authentication or user interaction. A fix is expected in an upstream Netty release.

## Affected products

- Netty Netty

## Timeline

- 2026-09-18: disclosed

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/jbossnetwork/restricted/listSoftware.html](https://access.redhat.com/jbossnetwork/restricted/listSoftware.html)

## Related threats

- [Netty HTTP/1 decoder request smuggling](https://junglewise.ai/threats/cve-2026-93562-a-flaw-was-found-in-netty-s-http-1-decoder-incomplete-validation)
- [Netty HTTP/1 to HTTP/2 conversion authority mismatch](https://junglewise.ai/threats/cve-2026-93569-netty-http-1-to-http-2-conversion-authority-mismatch)
- [Netty HTTP request smuggling via control characters in chunk size](https://junglewise.ai/threats/cve-2026-93566-netty-http-request-smuggling-via-control-characters-in-chunk-size)
- [Netty RtspDecoder method-token smuggling in RTSP parsing](https://junglewise.ai/threats/cve-2026-93565-netty-rtspdecoder-method-token-smuggling-in-rtsp-parsing)
- [Netty WebSocketServerExtensionHandler denial of service](https://junglewise.ai/threats/cve-2026-93558-netty-websocketserverextensionhandler-denial-of-service)