What’s Vulnerable › Vulnerabilities

CVE-2018-0476: Cisco IOS XE Software NAT Session Initiation Protocol Application Layer Gateway Denial of Service Vulnerability

• Severity: medium (CVSS 5.9 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 13.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-10-05 · updated 2026-06-17
• Weakness: CWE-399

Description

A vulnerability in the Network Address Translation (NAT) Session Initiation Protocol (SIP) Application Layer Gateway (ALG) of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper processing of SIP packets in transit while NAT is performed on an affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending crafted SIP packets via UDP port 5060 through an affected device that is performing NAT for SIP packets. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

Affected products

• Cisco IOS XE: 15.5(3)s5.1, 15.5(3)s6.1, 16.6.2

References

• http://www.securityfocus.com/bid/105419
• http://www.securitytracker.com/id/1041734
• http://www.securitytracker.com/id/1041737
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180926-sip-alg
• http://www.securityfocus.com/bid/105419
• http://www.securitytracker.com/id/1041734
• http://www.securitytracker.com/id/1041737
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180926-sip-alg

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