CVE Vulnerabilities


Improper Initialization

Published: Sep 25, 2019 | Modified: May 22, 2023
CVSS 3.x
CVSS 2.x
7.8 HIGH

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 transient SIP packets on which NAT is performed on an affected device. An attacker could exploit this vulnerability by using UDP port 5060 to send crafted SIP packets 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.


The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

Affected Software

Name Vendor Start Version End Version
Ios_xe Cisco 15.4(3)s (including) 15.4(3)s (including)
Ios_xe Cisco 15.5(3)s (including) 15.5(3)s (including)
Ios_xe Cisco 15.6(1)s (including) 15.6(1)s (including)
Ios_xe Cisco 16.3.1 (including) 16.3.1 (including)
Ios_xe Cisco 16.4.1 (including) 16.4.1 (including)
Ios_xe Cisco 16.5.1 (including) 16.5.1 (including)
Ios_xe Cisco 16.6.1 (including) 16.6.1 (including)
Ios_xe Cisco 16.7.1 (including) 16.7.1 (including)
Ios_xe Cisco 16.8.1 (including) 16.8.1 (including)
Ios_xe Cisco 16.9.1 (including) 16.9.1 (including)
Ios_xe Cisco 16.10.1 (including) 16.10.1 (including)
Ios_xe Cisco 16.11.1 (including) 16.11.1 (including)
Ios_xe Cisco 16.12.1 (including) 16.12.1 (including)

Potential Mitigations

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
  • For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable’s type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.