Known Exploited Vulnerabilities (KEV)

What Are Known Exploited Vulnerabilities?

Known Exploited Vulnerabilities (KEV) are security flaws that have been actively exploited by threat actors in real-world attacks. Unlike theoretical vulnerabilities that may never be used in an attack, KEVs present an immediate and confirmed risk to organizations.

Security agencies such as CISA (Cybersecurity and Infrastructure Security Agency) maintain a KEV catalog, listing vulnerabilities that are actively being exploited, requiring urgent attention from security teams. These vulnerabilities often appear in nation-state cyber campaigns, ransomware operations, and large-scale supply chain attacks.

Why Are KEVs Critical?

Not all vulnerabilities lead to a breach, but KEVs have already been used in attacks, making them the highest priority for remediation. Key risks include:

• Immediate Exploitation – KEVs are actively targeted, meaning unpatched systems are at high risk.

• Weaponized Exploits – Many KEVs have public proof-of-concept (PoC) exploits or automated attack tools, making it easy for threat actors to leverage them.

• Supply Chain Risks – KEVs are often found in widely used third-party software, libraries, or firmware, leading to cascading risks across multiple industries.

• Regulatory & Compliance Pressure – Many cybersecurity frameworks and government directives require immediate patching of KEVs to meet security standards.

How KEVs Are Identified and Managed

Security teams use threat intelligence feeds, vulnerability databases, and attack monitoring tools to track KEVs. Common methods include:

• CISA KEV Catalog – A publicly available, government-backed list of vulnerabilities with confirmed exploitation in the wild.

• Threat Intelligence & Dark Web Monitoring – Identifying which CVEs are being actively discussed, traded, or sold among cybercriminal groups.

• Exploit Prediction Scoring System (EPSS) – Assigning a probability score to predict which vulnerabilities are most likely to be exploited next.

• Security Patching & Remediation – Organizations prioritize KEVs above other vulnerabilities, ensuring rapid patching, virtual patching, or mitigation actions.

Best Practices for Defending Against KEVs

• Continuously monitor the KEV catalog and prioritize patching known exploited vulnerabilities.

• Apply compensating controls (e.g., segmentation, firewall rules, or exploit mitigations) if immediate patching isn’t possible.

• Automate vulnerability management to detect and respond to new KEVs before they can be leveraged in an attack.

• Align security policies with regulatory requirements that mandate remediation of actively exploited vulnerabilities.

By focusing on Known Exploited Vulnerabilities, organizations can significantly reduce risk exposure, prevent security breaches, and strengthen overall cyber resilience.