Security readout for executives and security teams
Plain-English summary
This flaw weakens 802.1X port authentication on specific Cisco Catalyst switches. An unauthenticated device already connected to the local network port may exchange broadcast traffic before authentication completes. The impact is limited, but it undermines a control often used to keep unknown devices off trusted networks.
Executive priority
Treat this as a controlled network remediation item, not an emergency internet-facing incident. Prioritize sites where 802.1X protects sensitive office, manufacturing, or shared-access networks from unknown local devices.
Technical view
CVE-2020-3231 is a CWE-284 access-control issue in Cisco IOS for Catalyst 2960-L Series and Catalyst CDB-8P switches. Broadcast traffic received on an 802.1X-enabled port is mishandled, allowing an unauthenticated adjacent attacker to send and receive broadcast traffic before port authentication.
Likely exposure
Exposure is most likely where affected Cisco Catalyst 2960-L Series or Catalyst CDB-8P switches run Cisco IOS 15.2(5a)E and use 802.1X on access ports. The attacker must be adjacent, meaning local Layer 2 or physical port access is required.
Exploitation context
The provided sources do not show known active exploitation, and the CVE is not listed as KEV. Exploitation requires adjacency and only allows pre-authentication broadcast traffic, not full authenticated network access according to the provided description.
Researcher notes
The CVSS vector is AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N with score 4.7. The vulnerability affects authentication boundary behavior, with limited confidentiality impact and no stated integrity or availability impact. Evidence is limited to the CVE record and Cisco advisory reference.
Mitigation direction
- Inventory Catalyst 2960-L and CDB-8P switches using 802.1X access ports.
- Check Cisco's advisory for fixed software, workarounds, and upgrade guidance.
- Restrict physical access to exposed access ports while remediation is pending.
- Disable unused switch ports or place them in controlled access states.
- Monitor for unexpected broadcast traffic from unauthenticated ports.
Validation and detection
- Confirm switch models and Cisco IOS versions against the Cisco advisory.
- Identify ports where 802.1X authentication is enabled.
- Review network telemetry for broadcast traffic before successful authentication.
- Validate remediation status after applying Cisco-recommended updates or workarounds.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-284: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-3231 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.7 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
4.7MediumVector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20200603 Cisco IOS Software for Catalyst 2960-L Series Switches and Catalyst CDB-8P Switches 802.1X Authentication Bypass VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Access Control
Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.