Security readout for executives and security teams
Plain-English summary
This flaw lets a nearby, unauthenticated wireless attacker send some IPv6 control traffic before a client reaches the normal authorized state. The documented impact is limited to ICMPv6 traffic and low integrity impact, not data theft or service outage. It still matters where wireless networks are physically reachable by untrusted people.
Executive priority
Treat as a targeted wireless-boundary issue rather than an internet-scale emergency. Prioritize remediation for corporate, guest, or public-facing Wi-Fi environments where attackers can get physically nearby.
Technical view
Cisco describes an incomplete ACL in IOS XE Wireless Controller Software for Catalyst 9800 Series Routers. Before a client is placed into RUN state, ICMPv6 traffic may be allowed when it should be controlled. CVSS 3.0 is 4.7 with adjacent access, low complexity, no privileges, no user interaction, changed scope, and low integrity impact.
Likely exposure
Exposure is most likely for organizations using Cisco IOS XE Wireless Controller Software on Catalyst 9800 Series Routers or related Catalyst 9000 wireless controller deployments with SSIDs reachable by nearby attackers. The source bundle does not provide specific affected versions.
Exploitation context
The bundle does not cite active exploitation, and CISA KEV status is false. Exploitation requires adjacent wireless reachability to the affected SSID and is limited by the documented outcome: sending ICMPv6 traffic before RUN state.
Researcher notes
Evidence supports an improper access control weakness, CWE-284, in pre-RUN-state filtering. The public bundle does not include affected version ranges, fixed releases, workarounds, proof-of-concept status, or exploitation evidence, so validation should start with Cisco’s advisory and local controller inventory.
Mitigation direction
- Review Cisco’s advisory for affected release and fixed software guidance.
- Apply Cisco-recommended fixed software if your deployment is listed as affected.
- Limit physical and wireless reachability of affected SSIDs where possible.
- Monitor for unexpected ICMPv6 traffic from clients not fully authorized.
Validation and detection
- Inventory Cisco IOS XE wireless controller deployments, especially Catalyst 9800 Series Routers.
- Compare running software versions and platform details against Cisco’s advisory.
- Review WLAN pre-authentication and client state controls for ICMPv6 handling.
- Check wireless logs for ICMPv6 activity before client RUN state.
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 lookupCVE-2020-3418 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:N/I:L/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:N/I:L/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:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20200924 Cisco IOS XE Wireless Controller Software for the Catalyst 9000 Family Improper Access Control 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.