CVE-2025-53521BigIP APM Vulnerability

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.

9.3 CRITICALEPSS 2.29%⚡ Known Exploited (CISA KEV)NVD: Analyzed

Last updated: 2026-10-08 12:10 UTC

OverviewCVSS details

9.3CRITICALCVSS 4.0

Score source: f5 (CNA)
NVD status: Analyzed
Published: Oct 15, 2025
Assigner: f5

Affected

BIG-IP (F5)

Versions: 17.5.0 before 17.5.1.3 · 17.1.0 before 17.1.3
Fixed in: 17.5.1.3, 17.1.3, 16.1.6.1

All affected versions →

Exploitation

Public exploit: None listed
CISA KEV: Listed · Mar 27, 2026
KEV due date: Mar 30, 2026
Ransomware use: Unknown
SSVC: Exploitation active · Automatable yes · Impact total

EPSS · FIRST, scored Nov 7

2.29%chance of exploitation in 30 days

Higher than 83.36% of CVEs

CVSS 4.0 · f5 (CNA)

9.3Critical

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: None
User interaction: None
Confidentiality impact: High
Integrity impact: High
Availability impact: High
Confidentiality (other systems): None
Integrity (other systems): None
Availability (other systems): None

CVSS 3.1 · f5 (CNA)

9.8Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

NVD status: Analyzed

Overview Affected Products References

NVD CVE.org

Overview

Severity

Score	Severity	Version	Vector String
9.3	CRITICAL	4.0f5 (CNA)	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8	CRITICAL	3.1f5 (CNA)	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA required action

⚡ Known exploited · remediation due Mar 30, 2026

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Details

CVE ID: CVE-2025-53521
Status: Analyzed
Assigner (CNA): f5
Published: Oct 15, 2025
Last modified: 2026-10-08 12:10 UTC
Weaknesses: CWE-121 · Stack-based Buffer Overflow

Sources

Refreshed hourly from the sources above. Last fetched 2026-11-07 16:30 UTC.