Info Security Magazine31 Mar 2026
NCSC Urges Immediate Patching of F5 BIG-IP Bug
The National Cyber Security Centre wants UK firms to patch CVE-2025-53521
Actively exploited vulnerability
CVE-2025-53521: F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.
CISA KEV source
27 Mar 2026 added
30 Mar 2026 remediation due
Affected product
F5 ยท BIG-IP
Known ransomware use: Unknown
Required action
Follow the source advisory and validate exposure in your environment.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Related Yasna coverage
Recent reporting that mentions CVE-2025-53521.
Dark Reading31 Mar 2026
F5 BIG-IP Vulnerability Reclassified as RCE, Under Exploitation
CVE-2025-53521 was initially disclosed in October as a high-severity denial-of-service (DoS) flaw, but new information has revealed the bug is actually much more dangerous.
Dark Reading31 Mar 2026
F5 BIG-IP Vulnerability Reclassified as RCE, Under Exploitation
CVE-2025-53521 was initially disclosed in October as a high-severity denial-of-service (DoS) flaw, but new information has revealed the bug is actually much more dangerous.
The Hacker News28 Mar 2026
CISA Adds CVE-2025-53521 to KEV After Active F5 BIG-IP APM Exploitation
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added a critical security flaw impacting F5 BIG-IP Access Policy Manager (APM) to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation