CVE-2019-5591: Fortinet FortiOS Default Configuration Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 446 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 18.6%
EPSS score, percentile 97.2 of all scored records
- How severe?
- 6.5 Medium
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline 3 May 2022. Apply updates per vendor instructions.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- FortiOS 6.2.0 and below.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 3 May 2022.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | FortiOS 6.2.0 and below. |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Fortinet FortiOS contains a default configuration vulnerability that may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the Lightweight Directory Access Protocol (LDAP) server.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2019-5591 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
- CISA marks it as known to be used in ransomware campaigns.
- The due date CISA sets for the required action is 3 May 2022.
- The CVE record was published on 14 Aug 2020, 446 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 6.5 (Medium), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 18.6% (percentile 97.2), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-306: Missing Authentication for Critical Function
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 14 Aug 2020 | CVE record published |
| 3 Nov 2021 | Added to CISA KEV |
| 3 May 2022 | CISA due date for the required action |
| 15 Aug 2026 | CVE record last updated |
References
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