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CVE-2025-53521

F5 BIG-IP Stack-Based Buffer Overflow Vulnerability

F5 BIG-IP CWE-121

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.

CVSS Score
9.8
Critical
EPSS — Exploit Probability
2.2%
Riskier than 81% of all CVEs
Exploitation
Confirmed in the wild
Used in ransomware campaigns
Remediation
Patch available
Federal deadline 2026-03-30
CISA 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. Deadline for federal agencies: 2026-03-30.

NVD entry Vendor patch PoC / advisory CISA KEV

3 articles across 3 outlets · first covered Mar 31, 2026 · latest Apr 6, 2026

Tracked incidents

vulnerability closed 8 articles
F5 BIG-IP APM vulnerability (CVE-2025-53521) reclassified as unauthenticated RCE

Coverage timeline