What’s Vulnerable › Vulnerabilities

CVE-2020-3510: Cisco IOS XE Software for Catalyst 9200 Series Switches Umbrella Connector Denial of Service Vulnerability

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-09-24 · updated 2026-06-17
• Weakness: CWE-388

Description

A vulnerability in the Umbrella Connector component of Cisco IOS XE Software for Cisco Catalyst 9200 Series Switches could allow an unauthenticated, remote attacker to trigger a reload, resulting in a denial of service condition on an affected device. The vulnerability is due to insufficient error handling when parsing DNS requests. An attacker could exploit this vulnerability by sending a series of malicious DNS requests to an Umbrella Connector client interface of an affected device. A successful exploit could allow the attacker to cause a crash of the iosd process, which triggers a reload of the affected device.

Affected products

• Cisco IOS XE: 16.12.1, 16.12.2, 17.1.1

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-umbrella-dos-t2QMUX37
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-umbrella-dos-t2QMUX37

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