{"id":"CVE-2026-121530","kind":"vulnerability","aliases":["CVE-2026-121530"],"related":[],"title":"Fortinet FortiOS: invalid token accepted after valid login grants improper access","description":"A improper authentication vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6 may allow a remote authenticated attacker to gain improper access control via an invalid token after entering a valid username and password","summary":"Fortinet FortiOS 7.6.0 through 7.6.6 has an improper authentication flaw where an invalid token is accepted after a valid username and password are entered. A remote attacker with valid credentials can gain access control they should not have.","severity":"medium","cvss":6.6,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["firewall","fortinet","fortios","vendor","vpn"],"not_affected_if":["no-remote-admin-or-vpn-login","other-fortios-versions"],"how_to_check":"- Check the FortiOS version on the appliance or in the management console against `7.6.0` through `7.6.6`","fix":"- FortiOS: move to a version outside `7.6.0` through `7.6.6`; the exact fixed version is unknown from the sources","status":"open","published_at":"2026-11-10T20:18:56+00:00","first_seen_at":"2026-11-10T20:46:04+00:00","triaged_at":"2026-11-10T20:48:04+00:00","updated_at":"2026-11-10T20:48:04+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-11-10T20:48:04Z","model":"claude-haiku-5-5","output":{"fix":"- FortiOS: move to a version outside `7.6.0` through `7.6.6`; the exact fixed version is unknown from the sources","reach":"network","title":"Fortinet FortiOS: invalid token accepted after valid login grants improper access","impact":"medium","summary":"Fortinet FortiOS 7.6.0 through 7.6.6 has an improper authentication flaw where an invalid token is accepted after a valid username and password are entered. A remote attacker with valid credentials can gain access control they should not have.","audience":"businesses","category":"vendor","nicknames":[],"who_cares":["fortios","fortinet","firewall","vpn"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"remote attacker with valid credentials gains improper access control","analyst_note":"Confirm the fixed FortiOS version and any workaround from the Fortinet PSIRT advisory; the sources give only the NVD description.","how_to_check":"- Check the FortiOS version on the appliance or in the management console against `7.6.0` through `7.6.6`\n- unknown for further configuration checks; the sources do not say","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["other-fortios-versions","no-remote-admin-or-vpn-login"],"who_is_affected":"Organisations running FortiOS 7.6.0 through 7.6.6 on firewalls or VPN gateways that accept remote logins. Attackers need a valid username and password first. Systems on other FortiOS branches are outside the stated range.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000748,"input_tokens":4536,"output_tokens":589,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-121530':14A,17A '-2026':13A,16A '7.6.0':25B,64C '7.6.6':27B,66C 'accept':5A,38B 'access':11A,55B,76C 'allow':68C 'attack':49B,72C 'authent':31B,59C,71C 'control':56B,77C 'credenti':52B 'cve':12A,15A 'enter':46B,83C 'firewal':18B 'flaw':32B 'fortinet':1A,19B,23B,62C 'fortio':2A,20B,24B,63C 'gain':54B,74C 'grant':9A 'improp':10A,30B,58C,75C 'invalid':3A,35B,80C 'login':8A 'may':67C 'password':44B,88C 'remot':48B,70C 'token':4A,36B,81C 'usernam':42B,86C 'valid':7A,41B,51B,85C 'vendor':21B 'via':78C 'vpn':22B 'vulner':60C","nicknames":[],"mitigations":[],"who_affected":"Organisations running FortiOS 7.6.0 through 7.6.6 on firewalls or VPN gateways that accept remote logins. Attackers need a valid username and password first. Systems on other FortiOS branches are outside the stated range.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["firewall","fortinet","fortios","medium","vendor","vpn"],"campaign_type":null,"search_a":"'-121530':14A,17A '-2026':13A,16A 'accept':5A 'access':11A 'cve':12A,15A 'fortinet':1A 'fortio':2A 'grant':9A 'improp':10A 'invalid':3A 'login':8A 'token':4A 'valid':7A","search_b":"'7.6.0':25B '7.6.6':27B 'accept':38B 'access':55B 'attack':49B 'authent':31B 'control':56B 'credenti':52B 'enter':46B 'firewal':18B 'flaw':32B 'fortinet':19B,23B 'fortio':20B,24B 'gain':54B 'improp':30B 'invalid':35B 'password':44B 'remot':48B 'token':36B 'usernam':42B 'valid':41B,51B 'vendor':21B 'vpn':22B","search_c":"'7.6.0':64C '7.6.6':66C 'access':76C 'allow':68C 'attack':72C 'authent':59C,71C 'control':77C 'enter':83C 'fortinet':62C 'fortio':63C 'gain':74C 'improp':58C,75C 'invalid':80C 'may':67C 'password':88C 'remot':70C 'token':81C 'usernam':86C 'valid':85C 'via':78C 'vulner':60C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T20:18:56+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","cvss_by":"psirt@fortinet.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121530","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121530","severity":null,"published_at":"2026-11-10T20:18:56+00:00","modified_at":"2026-11-10T20:18:56+00:00","first_seen_at":"2026-11-10T20:46:04+00:00","fetched_at":"2026-11-10T20:46:04+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}