Vulnerability Database

328,409

Total vulnerabilities in the database

CVE-2025-20137

A vulnerability in the access control list (ACL) programming of Cisco IOS Software that is running on Cisco Catalyst 1000 Switches and Cisco Catalyst 2960L Switches could allow an unauthenticated, remote attacker to bypass a configured ACL.

This vulnerability is due to the use of both an IPv4 ACL and a dynamic ACL of IP Source Guard on the same interface, which is an unsupported configuration. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device.

Note: Cisco documentation has been updated to reflect that this is an unsupported configuration. However, Cisco is publishing this advisory because the device will not prevent an administrator from configuring both features on the same interface. There are no plans to implement the ability to configure both features on the same interface on Cisco Catalyst 1000 or Catalyst 2960L Switches.

  • Published: May 7, 2025
  • Updated: Nov 16, 2025
  • CVE: CVE-2025-20137
  • Severity: Low
  • Exploit:

CVSS v3:

  • Severity: Low
  • Score: 4.7
  • AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Software From Fixed in
cisco / ios 15.2(5a)e 15.2(5a)e.x
cisco / ios 15.2(5b)e 15.2(5b)e.x
cisco / ios 15.2(5c)e 15.2(5c)e.x
cisco / ios 15.2(6)e 15.2(6)e.x
cisco / ios 15.2(6)e0c 15.2(6)e0c.x
cisco / ios 15.2(6)e1 15.2(6)e1.x
cisco / ios 15.2(6)e2 15.2(6)e2.x
cisco / ios 15.2(6)e2b 15.2(6)e2b.x
cisco / ios 15.2(6)e3 15.2(6)e3.x
cisco / ios 15.2(7)e 15.2(7)e.x
cisco / ios 15.2(7)e0a 15.2(7)e0a.x
cisco / ios 15.2(7)e0s 15.2(7)e0s.x
cisco / ios 15.2(7)e1 15.2(7)e1.x
cisco / ios 15.2(7)e1a 15.2(7)e1a.x
cisco / ios 15.2(7)e2 15.2(7)e2.x
cisco / ios 15.2(7)e3 15.2(7)e3.x
cisco / ios 15.2(7)e3k 15.2(7)e3k.x
cisco / ios 15.2(7)e4 15.2(7)e4.x
cisco / ios 15.2(7)e5 15.2(7)e5.x
cisco / ios 15.2(7)e6 15.2(7)e6.x
cisco / ios 15.2(7)e7 15.2(7)e7.x
cisco / ios 15.2(7)e8 15.2(7)e8.x
cisco / ios 15.2(7)e9 15.2(7)e9.x
cisco / ios 15.2(7)e10 15.2(7)e10.x
cisco / ios 15.2(7)e11 15.2(7)e11.x
cisco / ios 15.2(7)e12 15.2(7)e12.x
cisco / ios 15.2(7a)e0b 15.2(7a)e0b.x
cisco / ios 15.2(7b)e0b 15.2(7b)e0b.x
cisco / ios 15.2(8)e 15.2(8)e.x
cisco / ios 15.2(8)e1 15.2(8)e1.x
cisco / ios 15.2(8)e2 15.2(8)e2.x
cisco / ios 15.2(8)e3 15.2(8)e3.x
cisco / ios 15.2(8)e4 15.2(8)e4.x
cisco / ios 15.2(8)e5 15.2(8)e5.x
cisco / ios 15.2(8)e6 15.2(8)e6.x

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.