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Findings

CVE-2017-12231

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

Published Sep 28, 2017 · updated Jun 16, 2026 · cisco ios

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.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 28, 2017 · Catalog

    Detected

    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 d

  2. Mar 3, 2022 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Mar 24, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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 d

Required action

Apply updates per vendor instructions.

CISA due date Mar 24, 2022

Affected

  • cpe cisco/iosversion unspecified
  • vendor Cisco IOS softwareversion unspecified

Sources

  • CISA KEVCVE-2017-12231

    A vulnerability in the implementation of Network Address Translation (NAT) functionality in Cisco IOS could allow an unauthenticated, remote attacker to cause a denial of service.

    cisa.gov
  • CVE.orgCVE-2017-12231

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2017-12231

    30-day exploitation probability 7.1%

    first.org
  • NIST NVDCVE-2017-12231

    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 tra

    nvd.nist.gov

References

CVE-2017-12231 · ZeroDay Findings