CVE-2025-21091 in BIG-IP
Summary
by MITRE • 02/05/2025
When SNMP v1 or v2c are disabled on the BIG-IP, undisclosed requests can cause an increase in memory 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
The vulnerability identified as CVE-2025-21091 represents a memory exhaustion issue within F5 BIG-IP systems when SNMP v1 and v2c protocols are disabled. This weakness occurs during processing of undisclosed requests that are sent to the system, leading to unintended resource consumption patterns. The vulnerability specifically manifests when the system receives certain network traffic patterns that trigger memory allocation behaviors inconsistent with normal operational parameters. The issue arises from the system's handling of incoming requests that are not properly filtered or rejected when SNMP protocols are disabled, creating a scenario where memory resources gradually increase without proper bounds checking.
From a technical perspective, this vulnerability demonstrates characteristics consistent with CWE-400, which addresses unchecked resource consumption or resource exhaustion issues in software systems. The flaw occurs within the network protocol handling layer of the BIG-IP system where requests bypass normal SNMP protocol checks and trigger memory allocation routines. When SNMP v1 and v2c are disabled, the system should properly reject or ignore requests that would normally be processed through those protocols, but instead these requests cause memory allocation operations to occur. The undisclosed nature of the specific request patterns suggests that this could be exploited through various network traffic types that inadvertently trigger the problematic code path. This represents a failure in input validation and protocol handling within the system's network stack implementation.
The operational impact of CVE-2025-21091 can be significant for organizations relying on F5 BIG-IP systems for network infrastructure management. Memory resource exhaustion can lead to system performance degradation, application slowdowns, or complete system unavailability if memory consumption reaches critical levels. In high-traffic environments, this vulnerability could be exploited to cause denial of service conditions affecting critical network services. The gradual nature of memory increase means that the impact may not be immediately apparent but could accumulate over time, potentially leading to unexpected system failures. Organizations using BIG-IP systems in production environments face risk of service disruption and potential security implications if memory resources become exhausted, particularly in scenarios where the system handles large volumes of network traffic.
Security implications extend beyond simple resource exhaustion to include potential exploitation vectors that align with ATT&CK framework tactic TA0043, which covers resource exhaustion and denial of service. The vulnerability could be leveraged by attackers to perform sustained denial of service attacks against BIG-IP systems, particularly in environments where monitoring and alerting systems may not immediately detect gradual memory consumption patterns. Mitigation strategies should include implementing proper network segmentation to limit access to SNMP ports, deploying intrusion detection systems that can identify anomalous traffic patterns, and ensuring timely application of vendor security patches. Organizations should also consider implementing memory monitoring and alerting mechanisms to detect unusual resource consumption patterns that could indicate exploitation of this vulnerability. The recommended approach involves maintaining current software versions, applying security patches promptly, and conducting regular security assessments of network infrastructure components to prevent exploitation of such memory-related vulnerabilities.