Fortinet FortiOS Default Configuration Vulnerability
Fortinet · FortiOS
A default configuration flaw in Fortinet's FortiOS allows the device's LDAP-related functionality to be exploited, exposing it to attackers on the same subnet. An unauthenticated attacker on the same subnet, requiring no user interaction, can intercept sensitive information by impersonating the LDAP server.
A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 4/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 8 months after disclosure. Public exploit code (PoC-in-GitHub) appeared 5 years after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+8 mo
- Added to CISA KEVknown ransomware use; EU database agrees+15 mo
- Public exploit codePoC-in-GitHub+5 yrs
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
3 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 3Initial AccessTA0001
CVE-2019-5591 is a default configuration vulnerability in Fortinet's FortiOS, specifically affecting the FortiGate SSL VPN. This vulnerability allows an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating a Lightweight Directory Access Protocol (LDAP) server.
Credential AccessTA0006
CollectionTA0009
Detection
0 rules for this CVE · 44 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2019-5591 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
External Remote ServicesT113320 general rules
- External Remote SMB Logon from Public IPhightest
- OpenCanary - SSH Login Attempthightest
- OpenCanary - SSH New Connection Attempthightest
- OpenCanary - Telnet Login Attempthightest
- Running Chrome VPN Extensions via the Registry 2 VPN Extensionhightest
- Unusual Child Process of dns.exehightest
- Unusual File Deletion by Dns.exehightest
- Unusual File Modification by dns.exehightest
Adversary-in-the-MiddleT155710 general rules
- Suspicious Child Process of Notepad++ Updater - GUP.Exehighexperimental
- Uncommon File Created by Notepad++ Updater Gup.EXEhighexperimental
- Potential Suspicious Activity Using SeCEditmediumtest
- ISATAP Router Address Was Setmediumexperimental
- Notepad++ Updater DNS Query to Uncommon Domainsmediumexperimental
- Cisco BGP Authentication Failureslowtest
- Cisco LDP Authentication Failureslowtest
- Huawei BGP Authentication Failureslowtest
Data from Local SystemT100514 general rules
- OpenCanary - SMB File Open Requesthightest
- Potential Conti Ransomware Database Dumping Activity Via SQLCmdhightest
- SQLite Chromium Profile Data DB Accesshightest
- SQLite Firefox Profile Data DB Accesshightest
- VeeamBackup Database Credentials Dump Via Sqlcmd.EXEhightest
- Script Interpreter Spawning Credential Scanner - Linuxhighexperimental
- Script Interpreter Spawning Credential Scanner - Windowshighexperimental
- Shai-Hulud NPM Package Malicious Exfiltration via Curlhighexperimental
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX