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CISA Warns of F5 BIG

Cybersecuritynews •Guru Baran • March 28, 2026

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a newly disclosed vulnerability affecting F5 BIG-IP systems to its Known Exploited Vulnerabilities (KEV) catalog, warning that the flaw is being actively leveraged in real-world attacks. The vulnerability, tracked as CVE-2025-53521, was officially listed on March 27, 2026, with a remediation deadline of March 30, […]

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Active Exploitation of RCE Vulnerability in F5 BIG-IP APM Systems A critical unauthenticated remote code execution vulnerability, tracked as CVE-2025-53521, in F5's BIG-IP Access Policy Manager (APM) systems is currently being exploited. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added this vulnerability to its Known Exploited Vulnerabilities catalog on March 27, 2026, following an update from F5 regarding a data breach attributed to a sophisticated nation-state threat actor. The vulnerability has a CVSS score of 9.8, indicating its high severity. Organizations using F5 BIG-IP APM systems are at risk, as the flaw allows attackers to execute arbitrary code without authentication. F5 initially published a security advisory on October 15, 2025, when the breach was confirmed. The ongoing exploitation poses a significant threat to affected systems and their users. 23 sources 76

Extracted Entities

CVEs (1)

CVE-2025-53521

Platforms (1)

F5 Big-ip