Security readout for executives and security teams
Plain-English summary
FortiOS devices at version 6.2.0 and below may expose sensitive LDAP authentication information to an unauthenticated attacker on the same subnet. The business risk is credential or identity data exposure where affected FortiGate systems rely on LDAP and share local network space with untrusted hosts.
Executive priority
Treat this as urgent for FortiOS environments using LDAP, despite the medium CVSS score. KEV listing means exploitation has been observed, and the impact is sensitive information exposure. Prioritize internet-edge and shared-network appliances first.
Technical view
The vulnerability is a FortiOS default configuration issue, tracked as CWE-306, allowing adjacent-network attackers to impersonate the LDAP server and intercept sensitive information. CVSS 3.1 is 6.5 with adjacent attack vector, low complexity, no privileges, no user interaction, and high confidentiality impact.
Likely exposure
Exposure is most likely in FortiOS 6.2.0 and below deployments using LDAP authentication where attackers can access the same subnet as the FortiOS device or relevant LDAP traffic path.
Exploitation context
CISA lists CVE-2019-5591 in the Known Exploited Vulnerabilities catalog, supporting known exploitation. The provided sources do not include exploit details, scale, indicators, or proof-of-concept status.
Researcher notes
The source bundle confirms affected FortiOS 6.2.0 and below, adjacent-network attack scope, LDAP impersonation, and KEV status. It does not provide fixed versions, exploit mechanics, indicators, or compensating controls beyond referring to Fortinet guidance.
Mitigation direction
- Identify all FortiOS systems running 6.2.0 or below.
- Review Fortinet advisory FG-IR-19-037 for approved fixes or configuration guidance.
- Prioritize remediation for FortiOS devices using LDAP authentication.
- Reduce untrusted same-subnet access to affected FortiOS and LDAP paths.
- Monitor authentication logs for unusual LDAP server contact or failures.
Validation and detection
- Confirm FortiOS version on every FortiGate asset.
- Determine whether LDAP authentication is configured on affected systems.
- Verify network placement for same-subnet exposure to untrusted hosts.
- Check Fortinet advisory status before declaring remediation complete.
- Review logs for suspicious LDAP authentication behavior.
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-306: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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-2019-5591 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
- 6.5 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/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.
CISA KEV status
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:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.fortiguard.com/psirt/FG-IR-19-037CVE reference · x_refsource_CONFIRM
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-5591CVE reference · government-resource
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.
Missing Authentication for Critical Function
Missing Authentication for Critical Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.