CVE-2025-55036 is an out-of-bounds write vulnerability classified under CWE-787 affecting F5 BIG-IP SSL Orchestrator when configured with explicit forward proxy on a virtual server and the proxy connect feature enabled. The vulnerability arises from improper handling of certain undisclosed traffic, which leads to memory corruption. This memory corruption can cause instability or crashes, resulting in denial of service conditions. The affected versions include 15.1.0, 16.1.0, and 17.1.0, which are currently supported releases. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS v3.1 base score is 7.5, reflecting high severity primarily due to the impact on availability (A:H) while confidentiality and integrity remain unaffected. No public exploits have been reported yet, but the nature of the vulnerability suggests that attackers could craft specific network traffic to trigger the flaw. The absence of patches at the time of publication means organizations must rely on configuration changes and monitoring until updates are available. This vulnerability is particularly critical for environments where BIG-IP SSL Orchestrator is used to manage and secure encrypted traffic flows, as disruption could impact business continuity and security monitoring capabilities.

For European organizations, the primary impact of CVE-2025-55036 is the potential for denial of service on critical network security infrastructure. F5 BIG-IP devices are widely used in enterprise, government, and telecom sectors across Europe to manage SSL traffic and enforce security policies. An attacker exploiting this vulnerability could cause memory corruption leading to device crashes or reboots, disrupting secure communications and potentially exposing organizations to further attacks during downtime. This could affect availability of critical services such as VPNs, secure web gateways, and application delivery controllers. Financial institutions, healthcare providers, and public sector entities relying on BIG-IP for secure traffic orchestration are particularly vulnerable to operational disruptions. Additionally, the inability to inspect or forward SSL traffic properly could degrade overall network security posture. The lack of confidentiality or integrity impact reduces the risk of data breaches but does not diminish the operational risks associated with service outages. The vulnerability also poses a risk to supply chain security where managed service providers use BIG-IP appliances to secure multiple clients.

1. Immediately review BIG-IP SSL Orchestrator configurations and disable the proxy connect feature if it is not essential for business operations. 2. Monitor network traffic for unusual or malformed packets that could trigger the vulnerability, using IDS/IPS systems tuned for BIG-IP traffic patterns. 3. Implement strict network segmentation and access controls to limit exposure of BIG-IP management and proxy interfaces to untrusted networks. 4. Engage with F5 support to obtain any available patches or hotfixes as soon as they are released, and plan for rapid deployment. 5. Conduct thorough testing of patches in a staging environment to ensure stability before production rollout. 6. Maintain up-to-date asset inventories to identify all affected BIG-IP devices and prioritize remediation based on criticality. 7. Consider deploying additional redundancy or failover mechanisms to minimize service disruption in case of exploitation. 8. Educate network and security teams about this vulnerability to ensure rapid detection and response to any suspicious activity. 9. Review and update incident response plans to include scenarios involving BIG-IP device outages.