How severe is CVE-2019-5591?

CVE-2019-5591 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2019-5591 being actively exploited?

Yes. CVE-2019-5591 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2019-5591?

CVE-2019-5591 affects Fortinet Fortios. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-5591?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2019-5591 have an EU (EUVD) identifier?

Yes. CVE-2019-5591 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2019-15166. It is also flagged as exploited in the EUVD (since 2021-11-03).

When was CVE-2019-5591 published?

CVE-2019-5591 was published on 2020-08-14 and last updated on 2026-08-15.

CVE-2019-5591

CVE-2019-5591 is a medium-severity vulnerability in Fortinet Fortios with a CVSS 3.x base score of 6.5. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2021-11-03). The underlying weakness is classified as CWE-306.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 3.3
EPSS exploit prediction: 18% (97th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2021-11-03)
EU (EUVD) id: EUVD-2019-15166
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2021-11-03)
Weakness: CWE-306
Affected product: Fortinet Fortios
Published: 2020-08-14
Last modified: 2026-08-15

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.

Frequently asked questions

What is CVE-2019-5591?: A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.
How severe is CVE-2019-5591?: CVE-2019-5591 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2019-5591 being actively exploited?: Yes. CVE-2019-5591 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2019-5591?: CVE-2019-5591 affects Fortinet Fortios. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-5591?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2019-5591 have an EU (EUVD) identifier?: Yes. CVE-2019-5591 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2019-15166. It is also flagged as exploited in the EUVD (since 2021-11-03).
When was CVE-2019-5591 published?: CVE-2019-5591 was published on 2020-08-14 and last updated on 2026-08-15.

References

Affected products (1)

cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*

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