Vulnerability Database

383,371

Total vulnerabilities in the database

CVE-2025-20183 — cisco / asyncos

Improper Input Validation

A vulnerability in a policy-based Cisco Application Visibility and Control (AVC) implementation of Cisco AsyncOS Software for Cisco Secure Web Appliance could allow an unauthenticated, remote attacker to evade the antivirus scanner and download a malicious file onto an endpoint. 

The vulnerability is due to improper handling of a crafted range request header. An attacker could exploit this vulnerability by sending an HTTP request with a crafted range request header through the affected device. A successful exploit could allow the attacker to evade the antivirus scanner and download malware onto the endpoint without detection by Cisco Secure Web Appliance.

  • Published: Feb 5, 2025
  • Updated: Sep 13, 2026
  • CVE: CVE-2025-20183
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Medium
  • Score: 5.8
  • AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

CWEs:

Software Affected versions
cisco / asyncos = 11.8.0-414
cisco / asyncos = 11.8.0-429
cisco / asyncos = 11.8.0-453
cisco / asyncos = 11.8.1-023
cisco / asyncos = 11.8.3-018
cisco / asyncos = 11.8.3-021
cisco / asyncos = 11.8.4-004
cisco / asyncos = 12.0.1-268
cisco / asyncos = 12.0.1-334
cisco / asyncos = 12.0.2-004
cisco / asyncos = 12.0.2-012
cisco / asyncos = 12.0.3-005
cisco / asyncos = 12.0.3-007
cisco / asyncos = 12.0.4-002
cisco / asyncos = 12.0.5-011
cisco / asyncos = 12.5.1-011
cisco / asyncos = 12.5.1-043
cisco / asyncos = 12.5.2-007
cisco / asyncos = 12.5.2-011
cisco / asyncos = 12.5.3-002
cisco / asyncos = 12.5.4-005
cisco / asyncos = 12.5.4-011
cisco / asyncos = 12.5.5-004
cisco / asyncos = 12.5.5-005
cisco / asyncos = 12.5.5-008
cisco / asyncos = 12.5.6-008
cisco / asyncos = 14.0.1-014
cisco / asyncos = 14.0.1-040
cisco / asyncos = 14.0.1-053
cisco / asyncos = 14.0.1-503
cisco / asyncos = 14.0.2-012
cisco / asyncos = 14.0.3-014
cisco / asyncos = 14.0.4-005
cisco / asyncos = 14.0.5-007
cisco / asyncos = 14.1.0-032
cisco / asyncos = 14.1.0-041
cisco / asyncos = 14.1.0-047
cisco / asyncos = 14.5.0-498
cisco / asyncos = 14.5.0-537
cisco / asyncos = 14.5.0-673
cisco / asyncos = 14.5.1-008
cisco / asyncos = 14.5.1-016
cisco / asyncos = 14.5.1-510
cisco / asyncos = 14.5.1-607
cisco / asyncos = 14.5.2-011
cisco / asyncos = 14.5.3-033
cisco / asyncos = 15.0.0-322
cisco / asyncos = 15.0.0-355
cisco / asyncos = 15.1.0-287
cisco / asyncos = 15.2.0-116
cisco / asyncos = 15.2.0-164

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.