---
id: GHSA-v74w-7mr3-4qg3
title: 'Netty: Denial of Service in XmlFrameDecoder via CPU Exhaustion'
summary: 'Netty: Denial of Service in XmlFrameDecoder via CPU Exhaustion'
severity: high
cvss: 7.5
cwe:
  - CWE-400
vendor: netty
product: 'io.netty:netty-codec-xml'
ecosystem: maven
affected:
  - 'io.netty:netty-codec-xml >= 4.2.0.Final, <= 4.2.15.Final'
  - 'io.netty:netty-codec-xml <= 4.1.135.Final'
patched:
  - 'io.netty:netty-codec-xml 4.2.16.Final'
  - 'io.netty:netty-codec-xml 4.1.136.Final'
published: '2026-07-24'
updated: '2026-07-24'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-v74w-7mr3-4qg3'
references:
  - url: 'https://github.com/netty/netty/security/advisories/GHSA-v74w-7mr3-4qg3'
  - url: 'https://github.com/netty/netty/pull/17063'
  - url: 'https://github.com/netty/netty/pull/17065'
  - url: >-
      https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
  - url: >-
      https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
  - url: 'https://github.com/netty/netty/releases/tag/netty-4.1.136.Final'
  - url: 'https://github.com/netty/netty/releases/tag/netty-4.2.16.Final'
  - url: 'https://github.com/advisories/GHSA-v74w-7mr3-4qg3'
tags:
  - ghsa
  - maven
ingestedAt: '2026-07-24T17:34:27.482Z'
---

## Overview

### Summary
An attacker can cause Denial of Service by sending a specially crafted malicious XML payload (e.g., repeated `</` characters) to a Netty server utilizing XmlFrameDecoder, causing the server's EventLoop thread to exhaust CPU resources and become unresponsive.

### Details
`io.netty.handler.codec.xml.XmlFrameDecoder` suffers from a vulnerability resulting in CPU exhaustion. When `<` followed by `/` is encountered, the decoder scans the remaining buffer for a closing `>`.
Because the parser state is not saved between `decode()` invocations, an attacker can trickle-feed a payload of `</` characters. This forces the decoder to repeatedly rescan the entire accumulated buffer. A 1MB `maxFrameLength` is enough to completely hang a server's thread while it loops endlessly.

### Impact
Denial of Service via CPU Exhaustion. Any application utilizing Netty's XmlFrameDecoder is impacted. An unauthenticated remote attacker can exploit this flaw by sending a modest amount of malformed XML data to an exposed port.

## Affected packages

- `io.netty:netty-codec-xml >= 4.2.0.Final, <= 4.2.15.Final`
- `io.netty:netty-codec-xml <= 4.1.135.Final`

## Remediation

Upgrade to a patched release:

- `io.netty:netty-codec-xml 4.2.16.Final`
- `io.netty:netty-codec-xml 4.1.136.Final`