# CVE-2017-12231: Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability

> CVE-2017-12231: Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability. CVSS 7.5 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2017-12231
Last updated: 2026-01-14T14:53:00Z

- Published: 2017-09-28 07:00 UTC · Updated: 2026-01-14 14:53 UTC · Assigner: cisco
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 7.1%, 94th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2022-03-03, federal due date 2022-03-24, ransomware use: Unknown
- CWE: CWE-399

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- n/a: Cisco IOS

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2017-12231)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2017-12231)
- [https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-nat](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-nat)
- [http://www.securityfocus.com/bid/101039](http://www.securityfocus.com/bid/101039)
- [http://www.securitytracker.com/id/1039449](http://www.securitytracker.com/id/1039449)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2017-12231 · Markdown: https://rewindex.com/cve/CVE-2017-12231.md · JSON: https://rewindex.com/api/v1/cves/CVE-2017-12231 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:44:09.462Z