TI-2021-01290 Aliases CVE-2021-1566 GHSA-9pg8-7479-p4jw

Cisco Email Security Appliance and Cisco Web Security Appliance Certificate Validation Vulnerability

LOW 36CWE-296Published 2021-06-16 · Updated 2024-11-07

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Spoofing
Confidentiality · integrity · availability: High · High · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-295.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0067 52nd percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco Web Security Appliance (WSA)	all versions	—	No fix listed	CNA

Cisco Web Security Appliance (WSA) VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 4

CPE	Versions	Role	Vendor
cpe:2.3:a:cisco:email_security_appliance:-:::::::*	not specified by NVD	Vulnerable	Cisco
cpe:2.3:o:cisco:asyncos::::::::	before 12.5.3-035; 13.0 to before 13.0.0-030; 13.5 to before 13.5.3-010	Vulnerable	Cisco
cpe:2.3:a:cisco:web_security_appliance:-:::::::*	not specified by NVD	Vulnerable	Cisco
cpe:2.3:o:cisco:asyncos::::::::	before 11.8.3-021; 12.0.0 to before 12.0.3-005; 12.5.0 to before 12.5.1-043	Vulnerable	Cisco

cpe:2.3:a:cisco:email_security_appliance:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Cisco
cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* Versions before 12.5.3-035; 13.0 to before 13.0.0-030; 13.5 to before 13.5.3-010 Vulnerable ·Cisco
cpe:2.3:a:cisco:web_security_appliance:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Cisco
cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* Versions before 11.8.3-021; 12.0.0 to before 12.0.3-005; 12.5.0 to before 12.5.1-043 Vulnerable ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-1566
2026-10-03 Alias added: GHSA-9pg8-7479-p4jw

References

Advisory 1

20210616 Cisco Email Security Appliance and Cisco Web Security Appliance Certificate Validation Vulnerability

TI-2026-74174 Arbitrary file write in Cisco Secure Email Gateway via AMP feature KEVCVSS 3.1CRITICAL 9.8
TI-2026-53489 Cisco Secure Email Gateway SQL Injection Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2025-14683 Cisco Secure Email Gateway and Cisco Secure Email and Web Manager Remote Command Execution Vulnerability KEVCVSS 3.1CRITICAL 10.0
TI-2021-13698 Cisco Web Security Appliance Proxy Service Denial of Service Vulnerability CVSS 3.1HIGH 8.6
TI-2018-11020 Cisco Email Security Appliance URL Filtering Denial of Service Vulnerability CVSS 3.1HIGH 8.6
TI-2019-01567 Cisco Email Security Appliance Denial of Service Vulnerability CVSS 3.1HIGH 8.6

See all 55 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences