---
id: CVE-2025-20137
title: >-
  Cisco IOS Software on Cisco Catalyst 1000 and 2960L Switches Access Control
  List Bypass Vulnerability (CVE-2025-20137)
summary: >-
  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…
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'
cvssSource: vendor
vendor: Cisco
product: IOS
affected:
  - ios 15.2(5a)E
  - ios 15.2(5b)E
  - ios 15.2(5c)E
  - ios 15.2(6)E
  - ios 15.2(6)E1
  - ios 15.2(6)E0c
  - ios 15.2(6)E2
  - ios 15.2(6)E1a
  - ios 15.2(6)E1s
  - ios 15.2(7)E
  - ios 12.2(6)I1
  - ios 15.2(6)E2b
  - ios 15.2(7)E1
  - ios 15.2(7)E0a
  - ios 15.2(7)E0s
  - ios 15.2(6)E3
  - ios 15.2(7)E2
  - ios 15.2(7a)E0b
  - ios 15.2(7)E3
  - ios 15.2(7)E1a
  - ios 15.2(7b)E0b
  - ios 15.1(3)SVR1
  - ios 15.1(3)SVS
  - ios 15.1(3)SVR2
  - ios 15.2(7)E4
  - ios 15.1(3)SVS1
  - ios 15.1(3)SVR3
  - ios 15.1(3)SVT1
  - ios 15.2(7)E3k
  - ios 15.2(8)E
  - ios 15.2(8)E1
  - ios 15.1(3)SVT2
  - ios 15.2(7)E5
  - ios 15.1(3)SVU1
  - ios 15.2(7)E6
  - ios 15.1(3)SVU10
  - ios 15.2(8)E2
  - ios 15.1(3)SVV1
  - ios 15.1(3)SVU2
  - ios 15.1(3)SVT3
published: '2025-05-07'
updated: '2025-05-07'
sourceUpdated: '2025-05-07T16:00:00+00:00'
source: CSAF
sourceUrl: >-
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsgacl-pg6qfZk
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsgacl-pg6qfZk
  - url: 'https://software.cisco.com'
tags:
  - csaf
  - vendor-advisory
  - cisco
epss: 0.00285
epssPercentile: 0.19431
ingestedAt: '2026-10-14T11:46:43.835Z'
---

## Overview

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.

Cisco has not released software updates that address this vulnerability. There are workarounds that address this vulnerability.

## Vendor advisories

- **cisco-sa-ipsgacl-pg6qfZk** · Cisco · affected: IOS (67 versions) · updated 2025-05-07 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsgacl-pg6qfZk)

**Cisco IOS Software on Cisco Catalyst 1000 and 2960L Switches Access Control List Bypass Vulnerability**. Released 2025-05-07.

Affected:

- IOS 15.2(5a)E
- IOS 15.2(5b)E
- IOS 15.2(5c)E
- IOS 15.2(6)E
- IOS 15.2(6)E1
- IOS 15.2(6)E0c
- IOS 15.2(6)E2
- IOS 15.2(6)E1a
- IOS 15.2(6)E1s
- IOS 15.2(7)E
- IOS 12.2(6)I1
- IOS 15.2(6)E2b
- IOS 15.2(7)E1
- IOS 15.2(7)E0a
- IOS 15.2(7)E0s
- IOS 15.2(6)E3
- IOS 15.2(7)E2
- IOS 15.2(7a)E0b
- IOS 15.2(7)E3
- IOS 15.2(7)E1a
- IOS 15.2(7b)E0b
- IOS 15.1(3)SVR1
- IOS 15.1(3)SVS
- IOS 15.1(3)SVR2
- IOS 15.2(7)E4
- IOS 15.1(3)SVS1
- IOS 15.1(3)SVR3
- IOS 15.1(3)SVT1
- IOS 15.2(7)E3k
- IOS 15.2(8)E
- IOS 15.2(8)E1
- IOS 15.1(3)SVT2
- IOS 15.2(7)E5
- IOS 15.1(3)SVU1
- IOS 15.2(7)E6
- IOS 15.1(3)SVU10
- IOS 15.2(8)E2
- IOS 15.1(3)SVV1
- IOS 15.1(3)SVU2
- IOS 15.1(3)SVT3

## Remediation

Cisco has released software updates that address this vulnerability. https://software.cisco.com