CVE-2026-16192 Overview
CVE-2026-16192 affects IBM WebSphere Application Server Liberty versions 17.0.0.3 through 26.0.0.8. The vulnerability allows an authenticated remote attacker to trigger a denial of service condition when the restConnector-2.0 feature is enabled. The flaw is classified under CWE-674 (Uncontrolled Recursion), indicating that malicious input can exhaust server resources through excessive recursive processing.
Critical Impact
An authenticated attacker with low privileges can render the WebSphere Liberty server unavailable, disrupting business-critical Java applications running on affected instances.
Affected Products
- IBM WebSphere Application Server Liberty 17.0.0.3 through 26.0.0.8
- Deployments with the restConnector-2.0 feature enabled
- Java Enterprise workloads hosted on affected Liberty runtimes
Discovery Timeline
- 2026-07-28 - CVE-2026-16192 published to NVD
- 2026-07-29 - Last updated in NVD database
Technical Details for CVE-2026-16192
Vulnerability Analysis
The vulnerability resides in the restConnector-2.0 feature of IBM WebSphere Application Server Liberty. This feature exposes JMX (Java Management Extensions) operations over a REST interface for remote administration. When the feature is enabled, the connector processes incoming requests through parsing logic vulnerable to uncontrolled recursion.
An authenticated attacker can craft requests that force the connector into deeply nested processing paths. Each recursive call consumes stack or heap resources without proper bounds enforcement. Sustained exploitation exhausts server resources and causes the Liberty runtime to become unresponsive.
The attack requires network access and valid authentication credentials with low privileges. No user interaction is needed. Impact is limited to availability, with confidentiality effects constrained to the affected component. The Exploit Prediction Scoring System (EPSS) reports a probability of 0.268% for near-term exploitation.
Root Cause
The root cause is uncontrolled recursion [CWE-674] in the request processing routines of the restConnector-2.0 feature. The code fails to enforce depth limits when processing nested structures, allowing an attacker to drive the runtime into resource exhaustion.
Attack Vector
The attack vector is network-based against exposed REST management endpoints. An attacker authenticated to the JMX REST connector submits crafted payloads that trigger recursive processing. Repeated submissions degrade server responsiveness until the Liberty instance becomes unavailable. Refer to the IBM Security Advisory for authoritative technical details.
Detection Methods for CVE-2026-16192
Indicators of Compromise
- Unusual spikes in CPU or memory consumption on Liberty server processes coinciding with REST connector requests
- StackOverflowError or OutOfMemoryError entries in Liberty messages.log or console.log
- Repeated authenticated requests to /IBMJMXConnectorREST endpoints from a single source
- Sudden drops in application responsiveness or health-check failures for Liberty-hosted services
Detection Strategies
- Monitor HTTP access logs for anomalous request patterns targeting the JMX REST connector paths
- Correlate authentication events for Liberty administrative users with resource utilization metrics
- Alert on Java Virtual Machine (JVM) thread dumps showing deeply nested call stacks in restConnector classes
Monitoring Recommendations
- Enable verbose logging for the restConnector-2.0 feature and forward logs to a centralized SIEM
- Track baseline request rates to management endpoints and alert on statistical deviations
- Instrument JVM metrics such as heap usage, garbage collection frequency, and thread count for Liberty processes
How to Mitigate CVE-2026-16192
Immediate Actions Required
- Apply the fix referenced in the IBM Security Advisory as soon as it is available for your Liberty version
- Audit which Liberty servers have restConnector-2.0 enabled and disable the feature where remote JMX management is not required
- Restrict network access to the JMX REST connector endpoints to trusted management subnets only
- Rotate credentials for accounts authorized to access the REST connector
Patch Information
IBM has published guidance in the IBM Security Advisory. Administrators should consult the advisory for the specific interim fix or fix pack applicable to Liberty versions 17.0.0.3 through 26.0.0.8 and apply it during the next maintenance window.
Workarounds
- Remove the restConnector-2.0 feature from server.xml on Liberty instances that do not require remote JMX management
- Enforce IP allowlisting on the HTTPS endpoint hosting the REST connector using a reverse proxy or firewall
- Apply rate limiting to authenticated management endpoints to reduce the impact of abusive request volumes
- Require strong authentication and least-privilege role assignments for any account with access to the REST connector
# Configuration example - disable the restConnector-2.0 feature in server.xml
# Remove or comment out the following line from <featureManager>:
# <feature>restConnector-2.0</feature>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
