{"id":"CVE-2018-13383","kind":"vulnerability","aliases":["CVE-2018-13383"],"related":[],"title":"Fortinet FortiOS and FortiProxy: Fortinet FortiOS and FortiProxy Out-of-bounds Write","description":"A heap buffer overflow in Fortinet FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.10, 5.4.0 through 5.4.12, 5.2.14 and earlier and FortiProxy 2.0.0, 1.2.8 and earlier in the SSL VPN web portal may cause the SSL VPN web service termination for logged in users due to a failure to properly handle javascript href data when proxying webpages.","summary":"A heap buffer overflow in Fortinet FortiOS and FortiProxy's SSL VPN web service can crash the service for logged-in users. The sources tie it to ransomware use and in-the-wild exploitation, but do not confirm code execution.","severity":"medium","cvss":6.5,"epss":0.33647,"exploited":true,"exploited_at":"2022-01-10T00:00:00+00:00","products":[{"name":"Fortinet FortiOS and FortiProxy","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","fortinet","fortios","fortiproxy","infrastructure","ransomware","ssl-vpn"],"not_affected_if":["non-fortinet-gateway","ssl-vpn-disabled"],"how_to_check":null,"fix":"Apply the Fortinet update for FortiOS and FortiProxy per vendor instructions; the sources do not name the fixed version.","status":"open","published_at":"2019-05-29T18:29:00+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:31:47+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-10-23T21:31:47Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Fortinet update for FortiOS and FortiProxy per vendor instructions; the sources do not name the fixed version.","reach":"internet","impact":"medium","summary":"A heap buffer overflow in Fortinet FortiOS and FortiProxy's SSL VPN web service can crash the service for logged-in users. The sources tie it to ransomware use and in-the-wild exploitation, but do not confirm code execution.","category":"infrastructure","who_cares":["fortios","fortiproxy","ssl-vpn","fortinet"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Attacker crashes SSL VPN service; ransomware use reported, code execution unconfirmed","analyst_note":"Find the affected and fixed versions and the exact SSL VPN trigger in Fortinet's PSIRT advisory for CVE-2018-13383 and check whether public exploit details show code execution, not just crash.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["ssl-vpn-disabled","non-fortinet-gateway"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000494,"input_tokens":2853,"output_tokens":417,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Find the affected and fixed versions and the exact SSL VPN trigger in Fortinet's PSIRT advisory for CVE-2018-13383 and check whether public exploit details show code execution, not just crash.","search":"'-13383':16A,19A '-2018':15A,18A '1.2.8':97C '2.0.0':96C '5.2.14':91C '5.4.0':88C '5.4.12':90C '5.6.0':85C '5.6.10':87C '6.0.0':82C '6.0.4':84C 'and':22A 'bound':12A 'buffer':35B,77C 'caus':107C 'code':73B 'confirm':72B 'crash':48B 'cve':14A,17A 'data':127C 'due':118C 'earlier':93C,99C 'execut':74B 'exploit':24B,68B 'failur':121C 'fortinet':1A,5A,20A,25B,38B,80C 'fortio':2A,6A,26B,39B,81C 'fortios':21A 'fortiproxi':4A,8A,27B,41B,95C 'fortiproxy':23A 'handl':124C 'heap':34B,76C 'href':126C 'in-the-wild':64B 'infrastructur':28B 'javascript':125C 'log':53B,115C 'logged-in':52B 'may':106C 'out-of-bound':9A 'overflow':36B,78C 'portal':105C 'proper':123C 'proxi':129C 'ransomwar':29B,61B 'servic':46B,50B,112C 'sourc':57B 'ssl':31B,43B,102C,109C 'ssl-vpn':30B 'termin':113C 'tie':58B 'use':62B 'user':55B,117C 'vpn':32B,44B,103C,110C 'web':45B,104C,111C 'webpag':130C 'wild':67B 'write':13A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2019-05-29T18:29:00+00:00","kev":{"dateAdded":"2022-01-10","dueDate":"2022-07-10","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","cvss_by":"psirt@fortinet.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2018-13383","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-13383","severity":null,"published_at":"2022-01-10T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T19:35:26+00:00","note":null},{"source":"epss","external_id":"CVE-2018-13383","url":"https://api.first.org/data/v1/epss?cve=CVE-2018-13383","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-2018-13383","url":"https://nvd.nist.gov/vuln/detail/CVE-2018-13383","severity":null,"published_at":"2019-05-29T18:29:00+00:00","modified_at":"2026-06-17T01:39:18+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"}