Overview
CVE-2025-53521 has been added to the CISA Known Exploited Vulnerabilities catalog. Published on October 15, 2025. Threat actors are actively exploiting this vulnerability in real-world attacks.
When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE).
Threat Intelligence
| Metric | Value |
|---|---|
| CVE ID | CVE-2025-53521 |
| Severity | HIGH |
| CVSS Score | 0.0/10 |
| CISA KEV | ✅ Yes — Actively Exploited |
| KEV Date Added | March 27, 2026 |
| Remediation Deadline | March 30, 2026 |
| EPSS Score | 2.2% exploit probability |
| EPSS Percentile | Top 99% of all CVEs |
Why This Matters
This vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, which means threat actors are actively exploiting it in real-world attacks.
Federal agencies are required to remediate by March 30, 2026. All organizations should treat this deadline as a strong recommendation.
Recommended Actions
- Verify exposure — Determine if your environment uses the affected software.
- Apply patches — Update to the latest version as soon as a fix is available.
- Monitor for compromise — Check logs for unusual activity.
- Meet the deadline — CISA recommends remediation by March 30, 2026.
References
CVE data aggregated from the National Vulnerability Database (NVD), CISA Known Exploited Vulnerabilities catalog, and FIRST EPSS. Analysis updated as new intelligence becomes available. Last updated: 2026-03-31.