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CVE-2020-3147: Cisco Small Business Switches Denial of Service Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-01-30 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the web UI of Cisco Small Business Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of requests sent to the web interface. An attacker could exploit this vulnerability by sending a malicious request to the web interface of an affected device. A successful exploit could allow the attacker to cause an unexpected reload of the device, resulting in a DoS condition. This vulnerability affects firmware releases prior than 1.3.7.18

Affected products

• Cisco Sf300-08 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-24 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-24Mp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-24P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-24Pp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-48 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-48P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf300-48Pp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf302-08 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf302-08Mp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf302-08Mpp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf302-08P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf302-08Pp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf500-24 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf500-24P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf500-48 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sf500-48P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-08 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-08P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-10Fp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-18 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-24 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-24Fp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-24P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-26 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-26Fp Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-26P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-48 Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-48P Firmware: before 1.3.7.18 — fixed in 1.3.7.18
• Cisco Sg200-50 Firmware: before 1.3.7.18 — fixed in 1.3.7.18

How to fix

Upgrade to a fixed version: Cisco Sf300-08 Firmware 1.3.7.18; Cisco Sf300-24 Firmware 1.3.7.18; Cisco Sf300-24Mp Firmware 1.3.7.18; Cisco Sf300-24P Firmware 1.3.7.18; Cisco Sf300-24Pp Firmware 1.3.7.18; Cisco Sf300-48 Firmware 1.3.7.18; Cisco Sf300-48P Firmware 1.3.7.18; Cisco Sf300-48Pp Firmware 1.3.7.18; Cisco Sf302-08 Firmware 1.3.7.18; Cisco Sf302-08Mp Firmware 1.3.7.18; Cisco Sf302-08Mpp Firmware 1.3.7.18; Cisco Sf302-08P Firmware 1.3.7.18. Check the vendor advisory for mitigations.

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smlbus-switch-dos-R6VquS2u
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-smlbus-switch-dos-R6VquS2u

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