What’s Vulnerable › Vulnerabilities

CVE-2023-20072: Cisco IOS XE Software Fragmented Tunnel Protocol Packet Denial of Service Vulnerability

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-03-23 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the fragmentation handling code of tunnel protocol packets in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected system to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to the improper handling of large fragmented tunnel protocol packets. One example of a tunnel protocol is Generic Routing Encapsulation (GRE). An attacker could exploit this vulnerability by sending crafted fragmented packets to an affected system. A successful exploit could allow the attacker to cause the affected system to reload, resulting in a DoS condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability.

Affected products

• Cisco IOS XE: 17.9.1, 17.9.1a, 17.9.1w

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-gre-crash-p6nE5Sq5
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-gre-crash-p6nE5Sq5

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