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CVE-2018-0159: Cisco IOS and XE Software Internet Key Exchange Version 1 Denial-of-Service Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2022-03-03
• EPSS: 6.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-03-28 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the implementation of Internet Key Exchange Version 1 (IKEv1) functionality in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific IKEv1 packets. An attacker could exploit this vulnerability by sending crafted IKEv1 packets to an affected device during an IKE negotiation. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuj73916.

Affected products

• Cisco IOS: 15.3(3)s
• Cisco IOS XE: 15.3(3)s

References

• http://www.securityfocus.com/bid/103562
• http://www.securitytracker.com/id/1040595
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-ike-dos
• http://www.securityfocus.com/bid/103562
• http://www.securitytracker.com/id/1040595
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-ike-dos
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0159

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