VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 3 March 2022Ransomware use: unknown
Cisco IOS software

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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Mar 2022, 1,617 days after the CVE record was published.

How likely is exploitation in the next 30 days?
7.1%

EPSS score, percentile 94.2 of all scored records

How severe?
7.5 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 24 Mar 2022. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • Cisco IOS

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: 24 March 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

n/a Cisco IOS
StatusVersions
AffectedCisco IOS

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

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.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2017-12231 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Mar 2022.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 24 Mar 2022.
  • The CVE record was published on 28 Sep 2017, 1,617 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 7.5 (High), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 7.1% (percentile 94.2), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
28 Sep 2017CVE record published
3 Mar 2022Added to CISA KEV
24 Mar 2022CISA due date for the required action
14 Jan 2026CVE record last updated

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