CVE-2025-21087 in BIG-IP
Summary
by MITRE • 02/05/2025
When Client or Server SSL profiles are configured on a Virtual Server, or DNSSEC signing operations are in use, undisclosed traffic can cause an increase in memory and CPU resource utilization.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated
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Analysis
by VulDB Data Team • 10/21/2025
This vulnerability exists within SSL/TLS profile configurations on virtual servers and DNSSEC signing operations where specific traffic patterns can trigger resource exhaustion through undisclosed traffic channels. The flaw manifests when client or server SSL profiles are actively configured on virtual servers, creating potential attack vectors that exploit memory and CPU resource consumption patterns. The vulnerability becomes particularly pronounced during DNSSEC signing operations, where the combination of SSL profile configurations and signing activities creates conditions for resource utilization spikes that can impact system performance and availability.
The technical implementation of this vulnerability stems from insufficient resource management within the SSL/TLS processing pipeline and DNSSEC operations. When undisclosed traffic flows through these configured profiles, the system fails to properly throttle or limit resource allocation, leading to progressive memory consumption and increased CPU utilization. This behavior aligns with CWE-400 vulnerability classifications related to resource exhaustion and can be categorized under CWE-778 for insufficient logging or monitoring of resource consumption. The vulnerability represents a denial of service risk where legitimate system operations become degraded or unavailable due to excessive resource consumption.
Operational impact of this vulnerability extends beyond simple performance degradation to potential system instability and service disruption. The resource utilization increase can cause virtual servers to become unresponsive, leading to connection timeouts and service interruptions for legitimate users. Network administrators may experience difficulty in diagnosing the root cause due to the "undisclosed traffic" nature of the triggering conditions, making this vulnerability particularly challenging to detect and remediate in production environments. The impact is amplified in high-traffic scenarios where multiple SSL profiles and DNSSEC operations are concurrently active, creating cascading resource consumption effects that can compromise overall system reliability.
Mitigation strategies should focus on implementing strict traffic monitoring and resource allocation controls within SSL/TLS profile configurations. Network administrators should establish resource utilization thresholds and implement automatic scaling mechanisms to prevent uncontrolled resource consumption. Configuration reviews should ensure that SSL profiles are properly tuned to handle expected traffic loads and that DNSSEC signing operations are appropriately limited to prevent resource exhaustion. The implementation of intrusion detection systems and network monitoring tools can help identify unusual traffic patterns that may trigger this vulnerability. Additionally, regular system updates and patches should be applied to address any underlying software issues that contribute to the resource management flaws. Organizations should also consider implementing rate limiting mechanisms and traffic shaping policies to prevent malicious or abnormal traffic from causing excessive resource consumption in SSL/TLS and DNSSEC operations. This vulnerability demonstrates the importance of proper resource management in security-critical systems and aligns with ATT&CK technique T1499 for resource exhaustion and T1566 for credential harvesting through system compromise.