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CVE-2025-53521

CISA KEV

Published March 27, 2026 · Updated April 3, 2026

high

What This Means

# CVE-2025-53521: F5 BIG-IP APM Stack Buffer Overflow **What it is:** F5 BIG-IP Access Policy Manager (APM) contains a stack-based buffer overflow in unauthenticated code paths that permits remote code execution without valid credentials. **Impact:** An attacker can execute arbitrary code on affected BIG-IP systems, gaining full control of the appliance and any network traffic it inspects or forwards. This affects organizations using BIG-IP APM for authentication, SSL/TLS termination, or application access control. **Required actions:** Identify all BIG-IP APM deployments in your environment immediately. Check F5's advisory for patched versions and apply them as soon as testing allows. If patching cannot be completed quickly, implement network segmentation to restrict administrative access and monitor APM processes for unexpected behavior using your SIEM.

Official Description+

F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.

Affected Products

VendorProduct
F5BIG-IP

Patch Status

Patch by 2026-03-30

Recommended Actions

  1. Check if your systems use any of the affected products listed above.
  2. Apply vendor patches immediately if available.
  3. This vulnerability is in CISA's Known Exploited Vulnerabilities catalog — prioritize remediation.
  4. Monitor vendor advisories for updates and additional mitigations.
  5. Review logs for indicators of compromise related to CVE-2025-53521.

Related Coverage

Vvulnerability

CVE-2025-53521: F5 BIG-IP APM Stack-Based Buffer Overflow Enables Unauthenticated Remote Code Execution

CVE-2025-53521 is a stack-based buffer overflow in F5 BIG-IP Access Policy Manager (APM) that allows unauthenticated remote attackers to execute arbitrary code on affected systems. Successful exploitation can lead to full system compromise, session interception, and lateral movement through protected networks. CISA has added the vulnerability to the KEV catalog with a federal patch deadline of March 30, 2026.

CISA KEV·7d ago·3 min read