CVE-2025-53521
Published: April 11, 2026
Official Description
F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.
Technical Analysis
CVE-2025-53521 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2025-53521 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
News & Research Mentioning CVE-2025-53521
The National Cyber Security Centre wants UK firms to patch CVE-2025-53521
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added a critical security flaw impacting F5 BIG-IP Access Policy Manager (APM) to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation. The vulnerability in question is CVE-2025-53521 (CVSS v4 score: 9.3), which could allow a threat actor to achieve remote code execution. "When a [xlite_meta score:53 src:The Hacker News xlite_fp:1ce97caf0f107707661ec737e3602da94a77ab1b44c85f6aedbd4a959eeadf03]
CISA has added one new vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2025-53521 F5 BIG-IP Remote Code Execution Vulnerability This type of vulnerability is a frequent attack vector for malicious cyber actors and poses significant risks to the federal enterprise. Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities established the KEV Catalog as a living list of known Common Vulnerabilities and Exposures (CVEs) that carry significant risk to the federal enterprise. BOD 22-01 requires Federal Civilian Executive Branch (FCEB) agencies to remediate identified vulnerabilities by the due date to protect FCEB networks against active thr [xlite_meta score:48 src:CISA Alerts xlite_fp:68b51d789a5aa106bfa79844b4598a1f707f2bb233c1558ac9a281eecbbf6f55]
Quick Facts
Known Threat Actors
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2025-53521 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1