Summary
Netty: Denial of Service in XmlFrameDecoder via CPU Exhaustion
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.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
GHSA-V74W-7MR3-4QG3 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.2.16.Final, 4.1.136.Final); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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io.netty:netty-codec-xml to 4.2.16.Final or later; io.netty:netty-codec-xml to 4.1.136.Final or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-V74W-7MR3-4QG3? GHSA-V74W-7MR3-4QG3 is a high-severity uncontrolled resource consumption vulnerability in io.netty:netty-codec-xml (maven), affecting versions >= 4.2.0.Final, <= 4.2.15.Final. It is fixed in 4.2.16.Final, 4.1.136.Final. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is GHSA-V74W-7MR3-4QG3? GHSA-V74W-7MR3-4QG3 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of io.netty:netty-codec-xml are affected by GHSA-V74W-7MR3-4QG3? io.netty:netty-codec-xml (maven) versions >= 4.2.0.Final, <= 4.2.15.Final is affected.
- Is there a fix for GHSA-V74W-7MR3-4QG3? Yes. GHSA-V74W-7MR3-4QG3 is fixed in 4.2.16.Final, 4.1.136.Final. Upgrade to this version or later.
- Is GHSA-V74W-7MR3-4QG3 exploitable, and should I be worried? Whether GHSA-V74W-7MR3-4QG3 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-V74W-7MR3-4QG3 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-V74W-7MR3-4QG3?
- Upgrade
io.netty:netty-codec-xmlto 4.2.16.Final or later - Upgrade
io.netty:netty-codec-xmlto 4.1.136.Final or later
- Upgrade