CVE-2023-38264 Overview
CVE-2023-38264 is a denial of service vulnerability affecting the IBM SDK, Java Technology Edition's Object Request Broker (ORB) component. The vulnerability stems from improper enforcement of JEP 290 deserialization filters, specifically the MaxRef and MaxDepth parameters. This insecure deserialization flaw allows remote attackers to cause service disruption without requiring authentication or user interaction.
Critical Impact
Attackers can remotely trigger denial of service conditions by exploiting improperly enforced deserialization filters in IBM's Java ORB implementation, potentially causing widespread application outages.
Affected Products
- IBM SDK, Java Technology Edition ORB versions 7.1.0.0 through 7.1.5.21
- IBM SDK, Java Technology Edition ORB versions 8.0.0.0 through 8.0.8.21
- Applications utilizing IBM Java Software Development Kit with ORB functionality
Discovery Timeline
- 2024-05-14 - CVE-2023-38264 published to NVD
- 2025-08-14 - Last updated in NVD database
Technical Details for CVE-2023-38264
Vulnerability Analysis
The vulnerability resides in IBM's implementation of the Object Request Broker (ORB), a CORBA-compliant component that enables distributed object communication in Java applications. The core issue is the improper enforcement of JEP 290 (Java Enhancement Proposal 290) deserialization filters.
JEP 290, introduced in Java 9 and backported to earlier versions, provides mechanisms to filter incoming serialization data during deserialization operations. Two critical filter parameters, MaxRef and MaxDepth, are designed to prevent resource exhaustion attacks by limiting object graph complexity. MaxRef restricts the maximum number of internal references, while MaxDepth limits the nesting depth of objects being deserialized.
When these filters are not properly enforced, attackers can craft malicious serialized objects with deeply nested structures or excessive internal references. Processing such objects consumes excessive memory and CPU resources, leading to denial of service conditions. The network-accessible nature of ORB services means this vulnerability can be exploited remotely without authentication.
Root Cause
The root cause is classified as CWE-502 (Deserialization of Untrusted Data). IBM's ORB implementation fails to consistently apply the JEP 290 MaxRef and MaxDepth deserialization constraints under certain circumstances. This allows specially crafted serialized objects to bypass the intended resource consumption limits, enabling attackers to submit objects that trigger resource exhaustion during deserialization.
Attack Vector
The attack vector is network-based, requiring no privileges or user interaction. An attacker can target any exposed ORB service endpoint by sending maliciously crafted serialized Java objects. The attack methodology involves constructing objects with either extreme nesting depth or excessive internal references that exceed what the improperly enforced filters should prevent.
When the vulnerable ORB component processes these objects, it fails to halt deserialization at the configured thresholds. The resulting resource consumption (memory allocation for deep object graphs, CPU cycles for reference resolution) degrades application performance or causes complete service unavailability.
The attack surface includes any application utilizing IBM Java SDK's ORB functionality that accepts serialized data from untrusted sources, including enterprise middleware, distributed applications, and CORBA-based services.
Detection Methods for CVE-2023-38264
Indicators of Compromise
- Unusual memory consumption spikes in Java processes utilizing IBM SDK ORB components
- Abnormal CPU utilization patterns during object deserialization operations
- Excessive garbage collection activity in affected Java applications
- Application timeouts or unresponsiveness following ORB communication attempts
- Log entries indicating deserialization failures or resource exhaustion errors
Detection Strategies
- Monitor Java heap memory metrics for sudden spikes correlated with ORB activity
- Implement network traffic analysis to identify anomalous serialized object payloads targeting ORB endpoints
- Deploy application performance monitoring (APM) to detect degradation in ORB-dependent services
- Configure JVM monitoring to alert on deserialization filter violations or bypass attempts
Monitoring Recommendations
- Enable verbose logging for ORB deserialization operations to capture filter enforcement events
- Establish baseline metrics for normal ORB communication patterns and alert on deviations
- Monitor thread pool exhaustion in application servers handling ORB requests
- Implement rate limiting on ORB endpoints to mitigate potential exploitation attempts
How to Mitigate CVE-2023-38264
Immediate Actions Required
- Inventory all systems running IBM SDK Java Technology Edition versions 7.1.0.0 through 7.1.5.21 and 8.0.0.0 through 8.0.8.21
- Review the IBM Support Advisory for detailed patching guidance
- Prioritize patching systems with externally accessible ORB endpoints
- Consider network segmentation to limit ORB service exposure while patches are deployed
Patch Information
IBM has released security updates to address this vulnerability. Administrators should upgrade to patched versions of IBM SDK, Java Technology Edition as specified in the official advisory. The IBM X-Force Vulnerability Report (ID: 260578) provides additional technical context and remediation details.
Organizations should follow their standard change management procedures while prioritizing this update for production systems, particularly those with network-exposed ORB services.
Workarounds
- Restrict network access to ORB endpoints using firewall rules or network segmentation
- Implement additional application-layer filtering to validate serialized object sizes before processing
- Configure stricter JEP 290 filter settings at the JVM level as a defense-in-depth measure
- Consider disabling ORB functionality if not required by the application
# Example: Configure JVM-level serialization filters
# Add to java command line or configuration file
java -Djdk.serialFilter="maxarray=100000;maxdepth=20;maxrefs=5000;maxbytes=500000" -jar application.jar
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
