What is CVE-2017-12213?

CVE-2017-12213 is a medium-severity vulnerability in Cisco Catalyst 4000, classified under Improper Authentication. CVSS score: 4.3/10. Published 2017-09-07.

How severe is CVE-2017-12213?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Cisco Catalyst 4000

CVE-2017-12213

A vulnerability in the dynamic access control list (ACL) feature of Cisco IOS XE Software running on Cisco Catalyst 4000 Series Switches could allow an unauthenticated, adjacent attacker to cause dynamic ACL assignment to fail and the port to fail open. This could allow the attacker to pass traffic to the default VLAN of the affected port. The vulnerability is due to an uncaught error condition that may occur during the reassignment of the auth-default-ACL dynamic ACL to a switch port after 802.1x authentication fails. A successful exploit of this issue could allow a physically adjacent attacker to bypass 802.1x authentication and cause the affected port to fail open, allowing the attacker to pass traffic to the default VLAN of the affected switch port. Cisco Bug IDs: CSCvc72751.

Vulnerability class: Broken Authentication

Published 2017-09-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.3th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Cisco Catalyst 4000
Cisco iOS Xe
Cisco Catalyst 4000 Series Switches — versions Cisco Catalyst 4000 Series Switches

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906… (Mitigation, Vendor Advisory)
www.securitytracker.com/id/1039284 (VDB Entry, Third Party Advisory, vdb-entry)
www.securityfocus.com/bid/100663 (VDB Entry, Third Party Advisory, vdb-entry)

Frequently asked questions

What is CVE-2017-12213?: CVE-2017-12213 is a medium-severity vulnerability in Cisco Catalyst 4000, classified under Improper Authentication. CVSS score: 4.3/10. Published 2017-09-07.
How severe is CVE-2017-12213?: Medium severity. CVSS v3 base score is 4.3 out of 10.