CVE-2017-12231

Name: CVE-2017-12231
Creator: NVD / NIST
Published: 2017-09-29T01:34:48.747+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10Actively ExploitedEPSS 6.94%

Last modified Jun 17, 2026

CVE-2017-12231 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. CISA has confirmed active exploitation in the wild. EPSS estimates a 6.94% chance of exploitation in the next 30 days.

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

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

6.94%

93.3th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Mar 24, 2022.

Weakness Enumeration

CWE-399

Affected Software

Vendor	Product	Versions
Cisco	Ios	>= 12.4, <= 15.6

References

http://www.securityfocus.com/bid/101039Broken Link, Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1039449Broken Link, Third Party Advisory, VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-natVendor Advisory
http://www.securityfocus.com/bid/101039Broken Link, Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1039449Broken Link, Third Party Advisory, VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-natVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2017-12231US Government Resource

Timeline

Published: Sep 29, 2017
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2017-12231?

How severe is CVE-2017-12231?

CVE-2017-12231 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 6.94% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2017-12231?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-12231?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST