CVE-2025-53521
CriticalExploitedPublic exploitWhen a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE).
Published Oct 15, 2025 · Updated Oct 8, 2026
Key Facts
Patch immediately- CVE-2025-53521 is a critical-severity vulnerability (CVSS 9.3 v4) affecting Big-Ip Access Policy Manager (F5), BIG-IP.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 27, 2026. Public exploit code is available.
- EPSS estimates a 2.3% probability of exploitation in the next 30 days.
- Fixed versions are available, including BIG-IP 15.1.10.8, BIG-IP 16.1.6.1, BIG-IP 17.1.3.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v4
9.3
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (30-day exploit likelihood)
2.3%
Higher than 82.9% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2025-53521 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Mar 27, 2026 | Mar 30, 2026 | Not reported |
| Industry KEV feed | Mar 27, 2026 | Mar 30, 2026 | Not reported |
| CIRCL KEV | Mar 27, 2026 | Mar 30, 2026 | Not reported |
| ENISA EUVD | Mar 27, 2026 | n/a | Not reported |
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.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Big-Ip Access Policy ManagerF5 | See advisory | 15.1.10.8 |
| BIG-IP | >= 17.5.0 | 17.5.1.3 |
Patched Releases
BIG-IP
15.1.10.8, 16.1.6.1, 17.1.3, 17.5.1.3
Big-Ip Access Policy Manager
15.1.10.8, 16.1.6.1, 17.1.3, 17.5.1.3
Timeline
Publicly disclosed
Oct 15, 2025
Added to CISA KEV
Mar 27, 2026
Added to Industry KEV feed
Mar 27, 2026
Added to CIRCL KEV
Mar 27, 2026
Added to ENISA EUVD
Mar 27, 2026
Last updated
Oct 8, 2026
Weakness Type
- CWE-121 Stack-based Buffer Overflow
References
- advisoryVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE).
Affected: Big-Ip Access Policy Manager (F5); BIG-IP versions >= 17.5.0. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 27, 2026.
Yes. It was added on Mar 27, 2026 with a federal remediation due date of Mar 30, 2026.
Public exploit code is available.
Fixed versions are available, including BIG-IP 15.1.10.8, BIG-IP 16.1.6.1, BIG-IP 17.1.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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