How severe is CVE-2017-12231?

CVE-2017-12231 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which products are affected by CVE-2017-12231?

Affected package information for CVE-2017-12231 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2017-12231?

No patch has shipped for CVE-2017-12231 yet — track the cisco ios advisory for a fixed release and apply the workarounds below in the meantime.

How do I detect CVE-2017-12231 across my infrastructure?

Inventory every cisco ios deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2017-12231 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2017-12231?

O3 detects and blocks CVE-2017-12231 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2017-12231 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2017-12231, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2017-12231?

CVE-2017-12231 has an EPSS (Exploit Prediction Scoring System) score of 7.1%, placing it in the 94th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2017-12231 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2017-12231 (Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-03-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-03-24. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2017-12231?

CVE-2017-12231 is classified as CWE-399 (CWE-399). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2017-12231?

CVE-2017-12231 affects cisco ios. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2017-12231 published, and has it been updated?

CVE-2017-12231 was published on September 29, 2017 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2017-12231: IOS CWE-399 (High 7.5)

EPSS Exploitation Probability

via FIRST.org ↗

7.1%probability of exploitation in next 30 days

Lower Risk94th percentile+0.19%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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.

Affected Products

1 product · 1 configurations

OS

ioscisco

≥ 12.4 && ≤ 15.6

range

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every cisco ios deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2017-12231 yet — track the cisco ios advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2017-12231 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2017-12231. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 affect

O3 Security · Runtime Protection

Is CVE-2017-12231 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2017-12231 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

Protect my workloads How runtime protection works

CVE-2017-12231

EPSS Exploitation Probability

Description

Affected Products

Detection & mitigation playbook

Detect

Remediation status

Mitigate without a patch

How O3 protects you

Frequently Asked Questions

Is CVE-2017-12231 being exploited in your environment?