CVE-2025-53521
critical CISA KEVF5 BIG-IP Stack-Based Buffer Overflow Vulnerability
Vendor / product: F5 — BIG-IP
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
9.8
9.8 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Severity source: NVD CVSS v3.1 (f5sirt@f5.com)
Timeline (UTC)
Published: 2025-10-15 14:15
Modified: 2026-10-08 12:10
NVD status: Analyzed
Last synced 1 day ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Listed in CISA KEV
Added 2026-03-27 · due 2026-03-30
Known ransomware use: Unknown
Required action (CISA)
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected products
f5 / big-ip_access_policy_manager ≥15.1.0 <15.1.10.8, ≥16.1.0 <16.1.6.1, ≥17.1.0 <17.1.3, ≥17.5.0 <17.5.1.3
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://my.f5.com/manage/s/article/K000156741
References
- https://my.f5.com/manage/s/article/K000156741 f5sirt@f5.com
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53521 134c704f-9b21-4f2e-91b3-4a467353bcc0
Data sources
CISA KEV — fetched 2026-10-27 06:50 UTC · record ↗
NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗