CVE-2024-20263

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-01-26 · updated 2026-06-17
Weakness: CWE-284

Description

A vulnerability with the access control list (ACL) management within a stacked switch configuration of Cisco Business 250 Series Smart Switches and Business 350 Series Managed Switches could allow an unauthenticated, remote attacker to bypass protection offered by a configured ACL on an affected device. This vulnerability is due to incorrect processing of ACLs on a stacked configuration when either the primary or backup switches experience a full stack reload or power cycle. An attacker could exploit this vulnerability by sending crafted traffic through an affected device. A successful exploit could allow the attacker to bypass configured ACLs, causing traffic to be dropped or forwarded in an unexpected manner. The attacker does not have control over the conditions that result in the device being in the vulnerable state. Note: In the vulnerable state, the ACL would be correctly applied on the primary devices but could be incorrectly applied to the backup devices.

Affected products

Cisco Cbs250-16P-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-16T-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 through 2.5.9.54 — fixed in 3.4.0.17
Cisco Cbs250-24Fp-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24Fp-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24P-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24P-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24Pp-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24T-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-24T-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-48P-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-48P-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-48Pp-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-48T-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-48T-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8Fp-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8P-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8Pp-D Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8Pp-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8T-D Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs250-8T-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-12Np-4X Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-12Xs Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-12Xt Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16Fp-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16P-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16P-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16T-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16T-E-2G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-16Xts Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17
Cisco Cbs350-24Fp-4G Firmware: from 3.4 before 3.4.0.17; from 2.5 before 2.5.9.54 — fixed in 2.5.9.54, 3.4.0.17

How to fix

Upgrade to a fixed version: Cisco Cbs250-16P-2G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-16T-2G Firmware 3.4.0.17; Cisco Cbs250-24Fp-4G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24Fp-4X Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24P-4G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24P-4X Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24Pp-4G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24T-4G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-24T-4X Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-48P-4G Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-48P-4X Firmware 2.5.9.54, 3.4.0.17; Cisco Cbs250-48Pp-4G Firmware 2.5.9.54, 3.4.0.17. Check the vendor advisory for mitigations.

References

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