NCSC Urges Immediate Patching of Critical F5 BIG-IP Vulnerability

The UK’s National Cyber Security Centre (NCSC) has urged organizations to immediately patch a critical vulnerability in F5 BIG-IP systems, identified as CVE-2025-53521. The flaw affects unspecified versions of the BIG-IP platform, though no technical details about the exploit mechanism or impact were provided in the notice. The NCSC’s advisory targets UK firms, emphasizing the urgency of applying available patches to mitigate potential risks. No specific attack campaigns, exploitation instances, or affected user counts were disclosed. The notice does not include a release date for the patch or further contextual details about the vulnerability’s severity.