March 27, 2026 · Applied Cybernetics Group
CVE-2025-53521 — F5 BIG-IP
F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
- Added to KEV
2026-03-27- Federal due date
2026-03-30- Vendor
- F5
- Product
- BIG-IP
- EPSS
- 82.4th percentile (score 0.023, as of
2026-09-16) - NVD CVSS v3.1
- 9.8 (CRITICAL)
- Ransomware use
- Unknown
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2025-53521
CISA short description
F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
NVD description
When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE). Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.