# CVE-2026-93491: Netty HttpServerCodec denial of service via HTTP request pipelining

Source: https://junglewise.ai/threats/cve-2026-93491-netty-httpservercodec-denial-of-service-via-http-request  
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-2026-93491 · Severity: high · CVSS 7.5 · Published 2026-09-18

Netty is a widely-used networking library that provides HTTP protocol handling for Java applications. A remote attacker can exploit an unbounded memory growth vulnerability in the HTTP/1.1 request handler by pipelining multiple requests while withholding reads, causing the server to exhaust available memory and crash, resulting in service unavailability.

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

## Quick answers

**Is CVE-2026-93491 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93491 being exploited in the wild.

**How severe is CVE-2026-93491?** 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-2026-93491?** 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-2026-93491 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-93491?** 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 exists in Netty's HttpServerCodec HTTP/1.1 handler, which uses an internal methodOverflowQueue to buffer data during request pipelining. When an attacker sends multiple pipelined HTTP/1.1 requests on a single connection without triggering reads, the queue grows without bounds due to lack of size limits, causing unbounded heap memory consumption. No authentication is required; the attack is triggered by network-accessible HTTP services. A successful exploit leads to denial of service through memory exhaustion and process termination. Patches are expected to impose limits on the queue size.

## 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 reference-count leak in HAProxy PROXY-v2 decoder](https://junglewise.ai/threats/cve-2026-93564-netty-reference-count-leak-in-haproxy-proxy-v2-decoder)