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CVE-2021-34749

MEDIUM CVSS: 5.8 Published: 2021-08-18 Modified: 2026-06-17

Description

A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

Affected Platforms

Cisco Secure Firewall Management CenterCisco Ironport Web Security ApplianceCisco Firepower Management Center Virtual Appliance Firmware

Weakness Type

CWE-200, CWE-200

References