Security readout for executives and security teams
Plain-English summary
Fortinet Meru AP firmware has a design flaw that can let a highly privileged local attacker run unauthorized code or commands through crafted CLI input. The business risk is concentrated on organizations still running listed Meru AP versions, especially where administrative access is broadly available.
Executive priority
Prioritize if Meru AP devices remain in production or management access is shared widely. The vulnerability is not shown as actively exploited, but successful abuse has high device impact and could undermine wireless infrastructure trust.
Technical view
CVE-2021-42759 affects Fortinet Meru AP 8.6.1 and below and 8.5.5 and below. The CVSS 3.1 score is 6.7 with local attack vector, low complexity, high privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely limited to Fortinet Meru AP deployments running versions 8.6.1, 8.6.0, or 8.5.5 through 8.5.0. The CVSS vector indicates exploitation requires high privileges and local access, reducing broad internet exposure but increasing insider or compromised-admin risk.
Exploitation context
The source bundle does not identify CISA KEV listing or active exploitation. The CVSS temporal vector includes proof-of-concept maturity, but no source here provides exploit details. Treat this as a privileged post-authentication risk rather than a remote unauthenticated emergency.
Researcher notes
The key constraint is PR:H and AV:L, so validation should focus on firmware inventory, management-plane access, and privileged account exposure. The bundle does not include CWE details or a named fixed version, so remediation should be tied directly to Fortinet guidance.
Mitigation direction
- Inventory Fortinet Meru AP devices and record firmware versions.
- Check Fortinet advisory FG-IR-21-004 for vendor-approved fixed versions or mitigations.
- Restrict CLI and administrative access to trusted management networks and operators.
- Remove unnecessary privileged accounts and review administrator role assignments.
- Monitor administrative activity for unexpected command execution or configuration changes.
Validation and detection
- Confirm whether any Meru AP runs 8.6.1 or below, or 8.5.5 through 8.5.0.
- Verify administrative CLI access is limited and auditable.
- Review AP logs for unusual privileged sessions or command activity.
- Track remediation status against Fortinet advisory FG-IR-21-004.
- Document any compensating controls for devices awaiting vendor-directed remediation.
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.
CVE-2021-42759 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
- 6.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C
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:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C0.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.7MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.com/advisory/FG-IR-21-004CVE reference · x_refsource_CONFIRM
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.