Apr 62 min read
Thousands of F5 BIG-IP APM Instances Remain Vulnerable to Active RCE Exploits
Key Findings Over 14,000 F5 BIG-IP APM instances remain exposed online with active exploitation of CVE-2025-53521 Vulnerability reclassified from denial-of-service to critical remote code execution with CVSS score of 9.8 Originally disclosed in October 2025, but severity assessment updated in March 2026 after new findings Shadowserver tracks over 17,100 total BIG-IP APM fingerprints exposed globally, concentrated in US, Europe, and Asia CISA added flaw to Known Exploited Vuln
