What’s Vulnerable › Vulnerabilities

CVE-2023-20233

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-09-13 · updated 2026-06-17
• Weakness: CWE-476

Description

A vulnerability in the Connectivity Fault Management (CFM) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to incorrect processing of invalid continuity check messages (CCMs). An attacker could exploit this vulnerability by sending crafted CCMs to an affected device. A successful exploit could allow the attacker to cause the CFM service to crash when a user displays information about maintenance end points (MEPs) for peer MEPs on an affected device.

Affected products

• Cisco IOS XR Software: before 7.5.4; from 7.6 before 7.6.3; from 7.7 before 7.7.21; from 7.8 before 7.8.2; 7.9.0 — fixed in 7.5.4, 7.6.3, 7.7.21, 7.8.2

How to fix

Upgrade to a fixed version: Cisco IOS XR Software 7.5.4, 7.6.3, 7.7.21, 7.8.2. Check the vendor advisory for mitigations.

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xr-cfm-3pWN8MKt
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xr-cfm-3pWN8MKt

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