{"id":"CVE-2020-12820","aliases":["EUVD-2020-5103","GHSA-8hp7-6mr2-85pv"],"status":"published","title":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and...","description":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.","severity":{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L/E:U/RL:X/RC:X","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00887,"percentile":0.59593,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-121","CWE-787"],"published":"2024-12-19T10:57:31Z","modified":"2026-06-17T02:52:22Z","products":[{"vendor":"fortinet","product":"fortios"}],"references":[{"url":"https://fortiguard.fortinet.com/psirt/FG-IR-20-083","tags":["Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-12820"},{"url":"https://github.com/advisories/GHSA-8hp7-6mr2-85pv"}],"sources":{"cve":[{"id":"CVE-2020-12820","description":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.","status":"published","published":"2024-12-19T10:57:31.517Z","modified":"2024-12-20T17:25:13.362Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L/E:U/RL:X/RC:X","level":"medium","assessor":"cna"}],"cwes":["CWE-121"],"updated_at":"2026-11-02T14:35:53.236501Z"}],"euvd":[{"id":"EUVD-2020-5103","description":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.","status":"published","published":"2024-12-19T10:57:31Z","modified":"2024-12-20T17:25:13Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L/E:U/RL:X/RC:X","level":"medium"}],"updated_at":"2026-11-03T00:04:33.692832Z"}],"ghsa":[{"id":"GHSA-8hp7-6mr2-85pv","title":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and...","description":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.","status":"published","published":"2024-12-19T12:32:40Z","modified":"2025-01-21T21:31:50Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-121","CWE-787"],"updated_at":"2026-11-02T14:59:37.435968Z"}],"nvd":[{"id":"CVE-2020-12820","description":"Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.","status":"published","published":"2024-12-19T11:15:05.7Z","modified":"2026-06-17T02:52:22.41Z","cvss":[{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-121","CWE-787"],"updated_at":"2026-11-02T14:06:48.591569Z"}]}}