CVE-2019-5591
MediumExploitedPublic exploitA Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.
Published Aug 14, 2020 · Updated Aug 15, 2026
Key Facts
Patch immediately- CVE-2019-5591 is a medium-severity vulnerability (CVSS 6.5 v3.1) affecting Fortios (Fortinet).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 2, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 19% probability of exploitation in the next 30 days.
- Fixed versions are available, including Fortios <=6.2.0, Fortios 6.2.0.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
6.5
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS (30-day exploit likelihood)
19%
Higher than 97.2% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | May 3, 2022 | Known |
| Industry KEV feed | Apr 2, 2021 | May 3, 2022 | Known |
| CIRCL KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FortiosFortinet | >= FortiOS 6.2.0 and below. | 6.2.0 |
Patched Releases
Fortios
<=6.2.0
Timeline
Publicly disclosed
Aug 14, 2020
Added to Industry KEV feed
Apr 2, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Aug 15, 2026
Weakness Type
- CWE-306 Missing Authentication for Critical Function
References
- advisoryhttps://www.fortiguard.com/psirt/FG-IR-19-037
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.
Affected: Fortios (Fortinet) versions >= FortiOS 6.2.0 and below.. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 2, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of May 3, 2022.
Public exploit code is available.
Fixed versions are available, including Fortios <=6.2.0, Fortios 6.2.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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