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CVE-2019-1814: Cisco Small Business 300 Series Managed Switches DHCP Denial of Service Vulnerability

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-05-16 · updated 2026-06-17
• Weakness: CWE-400

Description

A vulnerability in the interactions between the DHCP and TFTP features for Cisco Small Business 300 Series (Sx300) Managed Switches could allow an unauthenticated, remote attacker to cause the device to become low on system memory, which in turn could lead to an unexpected reload of the device and result in a denial of service (DoS) condition on an affected device. The vulnerability is due to a failure to free system memory when an unexpected DHCP request is received. An attacker could exploit this vulnerability by sending a crafted DHCP packet to the targeted device. A successful exploit could allow the attacker to cause an unexpected reload of the device.

Affected products

• Cisco Sf300-08 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-24 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-24Mp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-24P Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-24Pp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-48 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-48P Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf300-48Pp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf302-08 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf302-08Mp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf302-08Mpp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf302-08P Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sf302-08Pp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10Mp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10Mpp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10P Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10Pp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-10Sfp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-20 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-28 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-28Mp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-28P Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-28Pp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-52 Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-52Mp Firmware: before 1.4.10.6 — fixed in 1.4.10.6
• Cisco Sg300-52P Firmware: before 1.4.10.6 — fixed in 1.4.10.6

How to fix

Upgrade to a fixed version: Cisco Sf300-08 Firmware 1.4.10.6; Cisco Sf300-24 Firmware 1.4.10.6; Cisco Sf300-24Mp Firmware 1.4.10.6; Cisco Sf300-24P Firmware 1.4.10.6; Cisco Sf300-24Pp Firmware 1.4.10.6; Cisco Sf300-48 Firmware 1.4.10.6; Cisco Sf300-48P Firmware 1.4.10.6; Cisco Sf300-48Pp Firmware 1.4.10.6; Cisco Sf302-08 Firmware 1.4.10.6; Cisco Sf302-08Mp Firmware 1.4.10.6; Cisco Sf302-08Mpp Firmware 1.4.10.6; Cisco Sf302-08P Firmware 1.4.10.6. Check the vendor advisory for mitigations.

References

• http://www.securityfocus.com/bid/108344
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-sb300sms-dhcp
• http://www.securityfocus.com/bid/108344
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-sb300sms-dhcp

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