CVE-2026-73507 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in io.netty:netty-codec-xml. A fix is available for io.netty:netty-codec-xml — see the affected versions and patch details below.
Netty: Denial of Service in XmlFrameDecoder via CPU Exhaustion
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73507.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-73507 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,066 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
io.netty:netty-codec-xml☕io.netty:netty-codec-xmlReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-xml | ≥ 4.2.0.Final&&< 4.2.16.Final | 4.2.16.Finalio.netty:netty-codec-xml:4.2.16.Final |
| ☕Maven | io.netty:netty-codec-xml | all versions | 4.1.136.Finalio.netty:netty-codec-xml:4.1.136.Final |
Affected Products
nettynettyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-xml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-codec-xml to 4.2.16.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73507 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
A flaw was found in Netty's XmlFrameDecoder component within the netty-codec-xml library. Red Hat products including JBoss EAP 7, Red Hat Fuse 7, Red Hat Single Sign-On 7, and Red Hat Integration Camel Spring Boot ship the netty-codec-xml library. However, these products do not utilize the XmlFrameDecoder class for…
Red Hat products do not use the vulnerable XmlFrameDecoder component. No mitigation is required for standard product deployments. Custom applications built on Red Hat middleware that explicitly instantiate XmlFrameDecoder should avoid processing untrusted XML input or upgrade to netty-codec-xml 4.1.136.Final or later.Source: Red Hat security advisory for CVE-2026-73507 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Apache Camel 4.18.4 for Spring Boot 3.5.16 | netty-codec-xml | RHSA-2026:71675 |
Frequently Asked Questions
Is CVE-2026-73507 in your dependencies?
Find it across Maven, including transitive dependencies.