Security readout for executives and security teams
Plain-English summary
FortiGate SSLVPN deployments on FortiOS 6.4.0 through 6.4.4 may incorrectly trust client certificates. An LDAP user could potentially connect with any certificate signed by a trusted Certificate Authority, weakening certificate-based access control. The public bundle does not show active exploitation or a named fixed version.
Executive priority
Treat this as a moderate-priority access-control issue for internet-facing VPN infrastructure. Prioritize confirmation and vendor-guided remediation because VPN authentication weaknesses can affect remote access trust, even without confirmed active exploitation in the supplied sources.
Technical view
CVE-2021-24012 is an improper certificate chain trust validation issue in Fortinet FortiOS SSLVPN. The described impact is that an LDAP user may authenticate using any certificate signed by a trusted CA. CVSS 3.1 is 6.5 with network attack vector, high attack complexity, no privileges, no user interaction, and changed scope.
Likely exposure
Exposure is limited to FortiGate systems running FortiOS 6.4.0 to 6.4.4 where SSLVPN and LDAP certificate-based authentication are relevant. Systems outside those versions are not identified as affected in the provided sources.
Exploitation context
The source bundle does not cite CISA KEV inclusion or other evidence of active exploitation. Exploitation is described as high complexity and depends on trusted CA handling in SSLVPN authentication for LDAP users.
Researcher notes
The provided evidence is narrow: affected versions, core behavior, CVSS, and Fortinet advisory reference. It does not provide exploit details, affected configurations beyond SSLVPN and LDAP users, or exact fixed releases. Avoid expanding scope beyond FortiOS 6.4.0 to 6.4.4.
Mitigation direction
- Review Fortinet advisory FG-IR-21-018 for vendor remediation guidance.
- Inventory FortiGate appliances and prioritize FortiOS 6.4.0 through 6.4.4.
- Confirm SSLVPN and LDAP certificate authentication exposure before risk acceptance.
- Apply Fortinet-recommended updates or configuration changes once verified from vendor guidance.
Validation and detection
- Identify all FortiGate devices and record FortiOS versions.
- Check whether any affected-version device exposes SSLVPN.
- Review SSLVPN authentication settings for LDAP and client certificate use.
- Review trusted CA configuration for SSLVPN authentication scope.
- Inspect VPN authentication logs for unexpected LDAP user certificate logins.
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
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CVE-2021-24012 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
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:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L2.23.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.com/advisory/FG-IR-21-018CVE 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.