How severe is CVE-2017-12238?

CVE-2017-12238 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which products are affected by CVE-2017-12238?

CVE-2017-12238 affects the following products: cisco ios.

How do I patch CVE-2017-12238?

No patch has shipped for CVE-2017-12238 yet — track the cisco ios advisory for a fixed release and apply the workarounds below in the meantime.

How do I detect CVE-2017-12238 across my infrastructure?

Inventory every cisco ios deployment and check each version against the affected-products list above.

How do I mitigate CVE-2017-12238 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Is CVE-2017-12238 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2017-12238, 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-2017-12238?

CVE-2017-12238 has an EPSS (Exploit Prediction Scoring System) score of 2.0%, placing it in the 81th 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-2017-12238 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2017-12238 (Cisco Catalyst 6800 Series Switches VPLS 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-2017-12238?

CVE-2017-12238 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-2017-12238?

CVE-2017-12238 affects cisco ios. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2017-12238 published, and has it been updated?

CVE-2017-12238 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.

🛡️

CISA KEV · ACTIVELY EXPLOITED

MEDIUM severity

CVE-2017-12238 — IOS

MEDIUM

CVE-2017-12238 is a medium-severity (CVSS 6.5) CWE-399 vulnerability in cisco ios. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-03-03) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

A vulnerability in the Virtual Private LAN Service (VPLS) code of Cisco IOS 15.0 through 15.4 for Cisco Catalyst 6800 Series Switches could allow an unauthenticated, adjacent attacker…

Published

Sep 29, 2017

Updated

Jun 17, 2026

Affected

1 product

Patched

See advisory

Exploits

2 known

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-03-03. Federal agencies were required to remediate by 2022-03-24.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2017-12238.

EPSS Exploitation Probability

via FIRST.org ↗

2.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2017-12238 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,492 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Description

A vulnerability in the Virtual Private LAN Service (VPLS) code of Cisco IOS 15.0 through 15.4 for Cisco Catalyst 6800 Series Switches could allow an unauthenticated, adjacent attacker to cause a C6800-16P10G or C6800-16P10G-XL type line card to crash, resulting in a denial of service (DoS) condition. The vulnerability is due to a memory management issue in the affected software. An attacker could exploit this vulnerability by creating a large number of VPLS-generated MAC entries in the MAC address table of an affected device. A successful exploit could allow the attacker to cause a C6800-16P10G or C6800-16P10G-XL type line card to crash, resulting in a DoS condition. This vulnerability affects Cisco Catalyst 6800 Series Switches that are running a vulnerable release of Cisco IOS Software and have a Cisco C6800-16P10G or C6800-16P10G-XL line card in use with Supervisor Engine 6T. To be vulnerable, the device must also be configured with VPLS and the C6800-16P10G or C6800-16P10G-XL line card needs to be the core-facing MPLS interfaces. Cisco Bug IDs: CSCva61927.

Affected Products

1 product · 1 configurations

ioscisco

≥ 15.0 && ≤ 15.4

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A vulnerability in the Virtual Private LAN Service (VPLS) code of Cisco …

cisa.govAPIMar 2022

A vulnerability in the Virtual Private LAN Service (VPLS) code of Cisco …

cisa.govCISAMar 2022

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every cisco ios deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2017-12238 yet — track the cisco ios advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2017-12238 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works