Vulnerability Database

383,371

Total vulnerabilities in the database

CVE-2016-6356 — cisco / email_security_appliance

Improper Input Validation

A vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to cause an affected device to stop scanning and forwarding email messages due to a denial of service (DoS) condition. Affected Products: This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco Email Security Appliances, both virtual and hardware appliances, if the software is configured to apply a message filter or content filter to incoming email attachments. The vulnerability is not limited to any specific rules or actions for a message filter or content filter. More Information: CSCuz63143. Known Affected Releases: 8.5.7-042 9.7.0-125. Known Fixed Releases: 10.0.0-125 9.1.1-038 9.7.2-047.

  • Published: Oct 28, 2016
  • Updated: Sep 13, 2026
  • CVE: CVE-2016-6356
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v2:

  • Severity: High
  • Score: 7.8
  • AV:N/AC:L/Au:N/C:N/I:N/A:C

CWEs:

Software Affected versions
cisco / email_security_appliance = 3.3.1-09
cisco / email_security_appliance = 7.1.0
cisco / email_security_appliance = 7.1.1
cisco / email_security_appliance = 7.1.2
cisco / email_security_appliance = 7.1.3
cisco / email_security_appliance = 7.1.4
cisco / email_security_appliance = 7.1.5
cisco / email_security_appliance = 7.3.0
cisco / email_security_appliance = 7.3.1
cisco / email_security_appliance = 7.3.2
cisco / email_security_appliance = 7.5.0
cisco / email_security_appliance = 7.5.1
cisco / email_security_appliance = 7.5.2
cisco / email_security_appliance = 7.5.2-201
cisco / email_security_appliance = 7.6.0
cisco / email_security_appliance = 7.6.1-000
cisco / email_security_appliance = 7.6.1-gpl-022
cisco / email_security_appliance = 7.6.2
cisco / email_security_appliance = 7.6.3-000
cisco / email_security_appliance = 7.6.3-025
cisco / email_security_appliance = 7.7.0-000
cisco / email_security_appliance = 7.7.1-000
cisco / email_security_appliance = 7.8.0
cisco / email_security_appliance = 7.8.0-311
cisco / email_security_appliance = 8.0.1-023
cisco / email_security_appliance = 8.0_base
cisco / email_security_appliance = 8.5.0-000
cisco / email_security_appliance = 8.5.0-er1-198
cisco / email_security_appliance = 8.5.6-052
cisco / email_security_appliance = 8.5.6-073
cisco / email_security_appliance = 8.5.6-074
cisco / email_security_appliance = 8.5.6-106
cisco / email_security_appliance = 8.5.6-113
cisco / email_security_appliance = 8.5.7-042
cisco / email_security_appliance = 8.6.0
cisco / email_security_appliance = 8.6.0-011
cisco / email_security_appliance = 8.9.0
cisco / email_security_appliance = 8.9.1-000
cisco / email_security_appliance = 8.9.2-032
cisco / email_security_appliance = 9.0.0
cisco / email_security_appliance = 9.0.0-212
cisco / email_security_appliance = 9.0.0-461
cisco / email_security_appliance = 9.0.5-000
cisco / email_security_appliance = 9.1.0
cisco / email_security_appliance = 9.1.0-011
cisco / email_security_appliance = 9.1.0-032
cisco / email_security_appliance = 9.1.0-101
cisco / email_security_appliance = 9.4.0
cisco / email_security_appliance = 9.4.4-000
cisco / email_security_appliance = 9.5.0-000
cisco / email_security_appliance = 9.5.0-201
cisco / email_security_appliance = 9.6.0-000
cisco / email_security_appliance = 9.6.0-042
cisco / email_security_appliance = 9.6.0-051
cisco / email_security_appliance = 9.7.0-125
cisco / email_security_appliance = 9.7.1-066

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.