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CVE-2021-1566

HIGH · CVSS 7.4EPSS 0.7%EU EUVD

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.

Key facts

CVSS score
7.4 (v3.1)
Severity
HIGH
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE)
CWE-296
EPSS score
0.7% (51th percentile)
In CISA KEV
No
In EU EUVD
Yes (EUVD-2021-7033)
Published
June 16, 2021
NVD last modified
June 17, 2026
Status
Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-7033 in the EU Vulnerability Database. Last updated in EUVD on November 7, 2024.

View on the EU Vulnerability Database

Affected products

  • cisco / asyncos
  • cisco / email security appliance
  • cisco / web security appliance

Certified products that may be affected

1 FIPS 140 or Common Criteria certified product, from automated matching by sec-certs.org.

References

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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