CVE DATABASE / CVE-2017-12231

CVE-2017-12231

Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability

CVSS 7.5 · HIGH ⚠ CISA KEV — ACTIVELY EXPLOITED

On the CISA KEV catalog

Confirmed exploited in the wild. Added 2022-03-03. Federal remediation due 2022-03-24.
Required action: Apply updates per vendor instructions.

Summary

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.

CVSS 3.1 breakdown

Base score	7.5 (HIGH)
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector	NETWORK
Attack complexity	LOW
Privileges required	NONE
User interaction	NONE
Scope	UNCHANGED
Confidentiality	NONE
Integrity	NONE
Availability	HIGH

Weakness type (CWE)

CWE-399

Affected products

Cisco iosCisco 1100-4g\/6g integrated services routerCisco 1100-4g integrated services routerCisco 1100-4gltegb integrated services routerCisco 1100-4gltena integrated services routerCisco 1100-4p integrated services routerCisco 1100-6g integrated services routerCisco 1100-8p integrated services routerCisco 1100-lte integrated services routerCisco 1100 integrated services routerCisco 1100 terminal services gatewaysCisco 1101-4p integrated services routerCisco 1101 integrated services routerCisco 1109-2p integrated services routerCisco 1109-4p integrated services routerCisco 1109 integrated services routerCisco 1111x-8p integrated services routerCisco 111x integrated services routerCisco 1120 integrated services routerCisco 1131 integrated services router

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References

Data: NIST NVD + CISA KEV. NVD last modified 2026-04-21. Always verify against the vendor advisory before acting.