CVE intelligence and bounded remediation
CVE-2021-34749 — Cisco Ironport Web Security Appliance security vulnerability
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.
- Severity
- High
- CVSS
- 8.6 (3.1)
- Published
- 2021-08-18
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-200
Affected products
- cisco / ironport_web_security_appliance / 14.5
- cisco / secure_firewall_management_center / 2.9.18
- cisco / firepower_management_center_virtual_appliance_firmware / 6.6.0
- cisco / firepower_management_center_virtual_appliance_firmware / 6.7.0
- cisco / firepower_management_center_virtual_appliance_firmware / 7.0.0
- cisco / firepower_management_center_virtual_appliance_firmware / 7.1.0
Matched remediation archetype
Information disclosure and sensitive data exposure
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Trace sensitive data through responses, errors, logs, metrics, traces, caches, exports, files, backups, and client bundles.
- Identify affected subjects, tenants, retention windows, access controls, and downstream copies without opening unnecessary sensitive records.
- Review metadata, timing, status, length, and existence signals as well as direct content disclosure.
Remediate safely
- Minimize collection and output, apply field-level authorization and redaction at a centralized boundary, and return generic external errors.
- Remove secrets and sensitive data from logs, artifacts, URLs, caches, and client-side bundles; rotate credentials that may have been exposed.
- Update the affected component and add synthetic-data tests for response, error, observability, and export paths.
Authoritative sources
Complete CVE record and remediation plan
The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.