Is CVE-2021-1566 actively exploited?

No active exploitation of CVE-2021-1566 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-1566 be exploited remotely?

Yes. CVE-2021-1566 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-1566?

CVE-2021-1566 has a CVSS score of 7.4 (HIGH).

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HIGH

CVE-2021-1566

CWE-296Published: June 16, 2021· Updated: Jun 17, 2026

7.4

CVSS v3.1

Official Description

A vulnerability in the Cisco Advanced Malware Protection (AMP) for Endpoints integration of Cisco AsyncOS for Cisco Email Security Appliance (ESA) and Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to intercept traffic between an affected device and the AMP servers. This vulnerability is due to improper certificate validation when an affected device establishes TLS connections. A man-in-the-middle attacker could exploit this vulnerability by sending a crafted TLS packet to an affected device. A successful exploit could allow the attacker to spoof a trusted host and then extract sensitive information or alter certain API requests.

NVD Source

Technical Analysis

CVE-2021-1566 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 7.4.