High severity · published Jun 16, 2021
CVE-2021-1566
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…
7.4
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AS
Asyncos · Cisco
before 12.5.3-035; 13.0 before 13.0.0-030; 13.5 before 13.5.3-010; before 11.8.3-021; 12.0.0 before 12.0.3-005; 12.5.0 before 12.5.1-043 · source: NVD
ES
Email Security Appliance · Cisco
All versions, or not specified · source: NVD
WS
Web Security Appliance · Cisco
All versions, or not specified · source: NVD
Affected product
AS
Asyncos
Cisco
More from Asyncos
10.0
CVE-2025-20393
Cisco Secure Email Gateway and Cisco Secure Email and Web Manager Remote Command Execution Vulnerability
9.8
CVE-2026-76519
Cisco Secure Email Gateway Arbitrary File Write Vulnerability
9.8
CVE-2026-76461
Cisco Secure Email Gateway SQL Injection Vulnerability
8.8
CVE-2022-20871
A vulnerability in the web management interface of Cisco AsyncOS for Cisco Secure Web Appliance, formerly Cisco Web Security Appliance (WSA), could allow an…
8.8
CVE-2022-20868
A vulnerability in the web-based management interface of Cisco Email Security Appliance, Cisco Secure Email and Web Manager and Cisco Secure Web Appliance could allow an…