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CVE-2025-53521

BigIP APM Vulnerability

Published: Oct 15, 2025Updated: Oct 21, 2025 Sources: CVE List NVDCWE-770
7.5HIGH
NVD MITRE
EPSS Score
2.3%
Top 17.5%
CISA KEV
Active Exploitation
Since Mar 27, 2026
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

In plain language

AI Act now

CVE-2025-53521 is a weakness in F5 BIG-IP that can let an attacker run code remotely without logging in, and it can also knock the system offline—if you use BIG-IP APM with an access policy on a virtual server, you should act now.

Executive summary

CVE-2025-53521 is an unauthenticated remote code execution in F5 BIG-IP (APM access policy configured on a virtual server), where crafted network traffic triggers code execution that can lead to denial of service; it is listed in CISA KEV and has been exploited in the wild.

If affected, business impact
Full device compromiseService outage / denial of serviceMalware persistence on serversCustomer login/session disruption

What to do now

  1. Check whether your F5 BIG-IP device has BIG-IP APM configured with an access policy on a virtual server.
  2. Determine your current BIG-IP version from the device’s system information screen or your vendor management tooling.
  3. Upgrade to one of the fixed versions: 17.5.1.3, 17.1.3, 16.1.6.1, or 15.1.10.8 (covers BIG-IP and the listed BIG-IP module names).
  4. If you cannot patch immediately, follow F5’s mitigations from the vendor remediation article linked in the advisory and restrict/limit exposure of the affected virtual server endpoints as directed by F5.
  5. After updating, review BIG-IP logs and system indicators for signs of compromise, and confirm the device continues to enforce the expected access-policy configuration.
Patch / advisory Usually a quick update

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-770

Affected Products

F5
commercial·US
BIG-IPOn-premNetwork Device
Networking Infrastructure / router-switch
big-ip access policy managerOn-premNetwork Device
Networking Infrastructure / firewall
big-ip advanced firewall managerOn-premSecurity Product
Networking Infrastructure / firewall
big-ip advanced web application firewallOn-premSecurity Product
Networking Infrastructure / firewall
big-ip analyticsOn-premNetwork Device
Networking Infrastructure / network-management
big-ip application acceleration managerOn-premNetwork Device
Networking Infrastructure / load-balancer-proxy
big-ip application security managerOn-premNetwork Device
Networking Infrastructure / firewall
big-ip application visibility and reportingOn-premNetwork Device
Networking Infrastructure / firewall
and 14 more affected products View all →

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Mar 27, 2026
Remediation due:Mar 30, 2026

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.

Official Patch Available
Is your org exposed to CVE-2025-53521?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://my.f5.com/manage/s/article/K000156741
my.f5.com
News mentions
4

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