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CVE-2017-12231

High 7.5 Exploited in the wild (KEV)

Confirmed active exploitation — CISA KEV catalog

Name
Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability
Added to catalog
Remediation due date (US federal)
Required action
Apply updates per vendor instructions.

Description

A vulnerability in the implementation of Network Address Translation (NAT) functionality in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to the improper translation of H.323 messages that use the Registration, Admission, and Status (RAS) protocol and are sent to an affected device via IPv4 packets. An attacker could exploit this vulnerability by sending a crafted H.323 RAS packet through an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to use an application layer gateway with NAT (NAT ALG) for H.323 RAS messages. By default, a NAT ALG is enabled for H.323 RAS messages. Cisco Bug IDs: CSCvc57217.

Metrics

CVSS 3.1
7.5 (HIGH) Score source: NVD CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS — exploit probability
7% (percentile: 94) as of 1 November 2026
CWE
CWE-399

Affected products

cisco: ios; cisco: 1100-4g\/6g integrated services router; cisco: 1100-4g integrated services router; cisco: 1100-4gltegb integrated services router; cisco: 1100-4gltena integrated services router; cisco: 1100-4p integrated services router; cisco: 1100-6g integrated services router; cisco: 1100-8p integrated services router; cisco: 1100-lte integrated services router; cisco: 1100 integrated services router; cisco: 1100 terminal services gateways; cisco: 1101-4p integrated services router; cisco: 1101 integrated services router; cisco: 1109-2p integrated services router; cisco: 1109-4p integrated services router

References