{"id":"CVE-2019-5591","kind":"vulnerability","aliases":["CVE-2019-5591"],"related":[],"title":"Fortinet FortiOS: Fortinet FortiOS Default Configuration Vulnerability","description":"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.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Fortinet FortiOS ships with a default configuration that lets an unauthenticated attacker on the same subnet impersonate the LDAP server. The attacker can intercept sensitive information such as LDAP credentials sent by the device.","severity":"high","cvss":6.5,"epss":0.18566,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Fortinet FortiOS","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","firewall","fortinet","fortios","infrastructure","ldap","ransomware"],"not_affected_if":["no-ldap-integration","not-on-same-subnet"],"how_to_check":null,"fix":"Apply updates per vendor instructions (CISA KEV required action); the specific fixed FortiOS version and the setting to change are unknown from the sources.","status":"open","published_at":"2020-08-14T16:15:16+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:41+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:39:41Z","model":"claude-haiku-5-5","output":{"fix":"Apply updates per vendor instructions (CISA KEV required action); the specific fixed FortiOS version and the setting to change are unknown from the sources.","reach":"network","impact":"medium","summary":"Fortinet FortiOS ships with a default configuration that lets an unauthenticated attacker on the same subnet impersonate the LDAP server. The attacker can intercept sensitive information such as LDAP credentials sent by the device.","category":"infrastructure","who_cares":["fortios","fortinet","firewall","ldap"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker on subnet intercepts LDAP credentials and other sensitive data","analyst_note":"Find the Fortinet PSIRT advisory for CVE-2019-5591 to get affected and fixed FortiOS versions and the exact default setting to change; check the CISA KEV entry for the required action.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-ldap-integration","not-on-same-subnet"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000484,"input_tokens":2866,"output_tokens":395,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Find the Fortinet PSIRT advisory for CVE-2019-5591 to get affected and fixed FortiOS versions and the exact default setting to change; check the CISA KEV entry for the required action.","search":"'-2019':9A,12A '-5591':10A,13A 'access':83C 'action':89C 'allow':66C 'appli':90C 'attack':34B,44B,69C 'cisa':87C 'configur':6A,29B,62C 'contain':59C 'credenti':52B 'cve':8A,11A 'default':5A,28B,61C 'devic':56B 'directori':82C 'exploit':16B 'firewal':17B 'fortinet':1A,3A,14A,18B,23B,57C 'fortio':2A,4A,19B,24B,58C 'fortios':15A 'imperson':39B,79C 'inform':48B,77C 'infrastructur':20B 'instruct':94C 'intercept':46B,75C 'ldap':21B,41B,51B,85C 'let':31B 'lightweight':81C 'may':65C 'per':92C 'protocol':84C 'ransomwar':22B 'requir':88C 'sensit':47B,76C 'sent':53B 'server':42B,86C 'ship':25B 'subnet':38B,73C 'unauthent':33B,68C 'updat':91C 'vendor':93C 'vulner':7A,63C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2020-08-14T16:15:16+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2019-5591","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-5591","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T10:39:08+00:00","note":null},{"source":"epss","external_id":"CVE-2019-5591","url":"https://api.first.org/data/v1/epss?cve=CVE-2019-5591","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2019-5591","url":"https://nvd.nist.gov/vuln/detail/CVE-2019-5591","severity":null,"published_at":"2020-08-14T16:15:16+00:00","modified_at":"2026-08-15T04:17:41+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}