CVE-2024-23076 Overview
CVE-2024-23076 describes a reported null pointer dereference [CWE-476] in JFreeChart v1.5.4, a Java chart library maintained by JFree. The issue is located in the /labels/BubbleXYItemLabelGenerator.java component and can trigger a NullPointerException at runtime. The vulnerability affects the availability of applications that render bubble XY charts using unchecked inputs.
This CVE is disputed by multiple third parties. They contend that no reasonable evidence supports classifying the behavior as a security vulnerability. The report may have originated from an automated tool that lacks robust validation for genuine security issues.
Critical Impact
A remote attacker can trigger a NullPointerException in applications rendering charts with BubbleXYItemLabelGenerator, causing a denial of service condition. The finding is disputed and may not represent an exploitable security flaw.
Affected Products
- JFree JFreeChart version 1.5.4
- Java applications embedding BubbleXYItemLabelGenerator for chart labels
- Downstream libraries and services depending on JFreeChart 1.5.4
Discovery Timeline
- 2024-04-10 - CVE-2024-23076 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-23076
Vulnerability Analysis
JFreeChart 1.5.4 contains a reported null pointer dereference in BubbleXYItemLabelGenerator.java, part of the label generation subsystem. When the generator processes a dataset lacking expected numeric values for the bubble size dimension, the code path can dereference a null reference. This produces an unhandled NullPointerException that propagates to the caller.
The reported impact is limited to application availability. Confidentiality and integrity are not affected. Because chart rendering typically runs in-process with the host application, a triggered exception can interrupt request handling or crash server-side rendering threads.
The finding is disputed. Reviewers argue that raising a NullPointerException when passed malformed data is standard Java behavior rather than a security defect. Applications supplying validated datasets are not affected.
Root Cause
The root cause is missing null checks in the label generation logic. BubbleXYItemLabelGenerator retrieves the Z-value from an XYZDataset and formats it without verifying that the returned object is non-null. When the dataset entry is absent or unset, the subsequent method call on the null reference throws the exception.
Attack Vector
Exploitation requires that an attacker supply or influence dataset input consumed by a component using BubbleXYItemLabelGenerator. In server-side chart generation, this could occur where user-controlled data is charted without validation. No authentication or user interaction is required if such a path is exposed over the network.
No verified proof-of-concept code exists in public repositories for this dispute-flagged CVE. Refer to the GitHub JFreeChart Repository and the GitHub Gist Resource for the original report.
Detection Methods for CVE-2024-23076
Indicators of Compromise
- Repeated java.lang.NullPointerException stack traces originating in org.jfree.chart.labels.BubbleXYItemLabelGenerator
- Application crashes or request failures correlated with bubble chart rendering endpoints
- Unexpected termination of chart-rendering worker threads in server logs
Detection Strategies
- Inventory Java applications that bundle jfreechart-1.5.4.jar using software composition analysis tooling
- Search application logs for exception traces referencing BubbleXYItemLabelGenerator or XYZDataset.getZValue
- Review web-facing endpoints that accept user-supplied dataset values feeding into JFreeChart
Monitoring Recommendations
- Alert on spikes in HTTP 5xx responses from services that render charts on demand
- Track thread and process crash counts on chart-rendering servers as an availability signal
- Enable centralized log aggregation for JVM exceptions to catch repeated dereference patterns
How to Mitigate CVE-2024-23076
Immediate Actions Required
- Validate all dataset inputs before passing them to JFreeChart label generators, rejecting null or missing Z-values
- Wrap chart-rendering calls in exception handlers so a NullPointerException cannot terminate the calling thread
- Restrict untrusted network input from directly influencing chart datasets
- Monitor the GitHub JFreeChart Repository for a fixed release addressing the dispute
Patch Information
No vendor advisory or fixed version is listed in the NVD entry at time of publication. Because the CVE is disputed, upstream JFree may not release a security-labeled patch. Track the JFreeChart Official Site and the project repository for future releases beyond 1.5.4.
Workarounds
- Subclass BubbleXYItemLabelGenerator and override generateLabelString to return an empty string when the Z-value is null
- Pre-filter XYZDataset entries to remove items with missing values before rendering
- Isolate chart generation in a separate worker process so an exception does not affect the primary application
# Example: identify vulnerable JFreeChart 1.5.4 artifacts in a build tree
find . -name 'jfreechart-1.5.4*.jar' -print
mvn dependency:tree | grep 'jfreechart:1.5.4'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
