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CVE-2020-3496: Cisco Small Business Smart and Managed Switches Denial of Service Vulnerability

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-26 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the IPv6 packet processing engine of Cisco Small Business Smart and Managed Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient validation of incoming IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet through an affected device. A successful exploit could allow the attacker to cause the switch management CLI to stop responding, resulting in a DoS condition. This vulnerability is specific to IPv6 traffic. IPv4 traffic is not affected.

Affected products

• Cisco Sf200-24 Firmware: through 2.5.5.47
• Cisco Sf200-24Fp Firmware: through 2.5.5.47
• Cisco Sf200-24P Firmware: through 2.5.5.47
• Cisco Sf200-48 Firmware: through 2.5.5.47
• Cisco Sf200-48P Firmware: through 2.5.5.47
• Cisco Sf250-24 Firmware: through 2.5.5.47
• Cisco Sf250-24P Firmware: through 2.5.5.47
• Cisco Sf250-48 Firmware: through 2.5.5.47
• Cisco Sf250-48Hp Firmware: through 2.5.5.47
• Cisco Sf300-08 Firmware: through 2.5.5.47
• Cisco Sf300-24 Firmware: through 2.5.5.47
• Cisco Sf300-24Mp Firmware: through 2.5.5.47
• Cisco Sf300-24P Firmware: through 2.5.5.47
• Cisco Sf300-24Pp Firmware: through 2.5.5.47
• Cisco Sf300-48 Firmware: through 2.5.5.47
• Cisco Sf300-48P Firmware: through 2.5.5.47
• Cisco Sf300-48Pp Firmware: through 2.5.5.47
• Cisco Sf302-08 Firmware: through 2.5.5.47
• Cisco Sf302-08Mp Firmware: through 2.5.5.47
• Cisco Sf302-08Mpp Firmware: through 2.5.5.47
• Cisco Sf302-08P Firmware: through 2.5.5.47
• Cisco Sf302-08Pp Firmware: through 2.5.5.47
• Cisco Sf350-48 Firmware: through 2.5.5.47
• Cisco Sf350-48Mp Firmware: through 2.5.5.47
• Cisco Sf350-48P Firmware: through 2.5.5.47
• Cisco Sf500-24 Firmware: through 2.5.5.47
• Cisco Sf500-24P Firmware: through 2.5.5.47
• Cisco Sf500-48 Firmware: through 2.5.5.47
• Cisco Sf500-48P Firmware: through 2.5.5.47
• Cisco Sf550X-24 Firmware: through 2.5.5.47

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sbss-ipv6-dos-tsgqbffW
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sbss-ipv6-dos-tsgqbffW

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